Add support for python 3.12

[JWCook]

It looks like requests-cache is currently compatible with python 3.12, with a few minor exceptions:

• Multiprocess usage with SQLite
• In-memory cache reads responses twice on request
• DeprecationWarning with datetime.utcnow()

Errors

Currently seeing a few test errors under python 3.12, including sqlite3.InterfaceError: bad parameter or other API misuse.

At first glance this looks like it might be a breaking change in the current dev build of 3.12 in the sqlite3 module, specifically with multithreaded usage.

Example logs:

=================================== FAILURES ===================================
_______________ TestMemoryCache.test_response_no_duplicate_read ________________
[gw0] linux -- Python 3.12.0 /home/runner/work/requests-cache/requests-cache/.venv/bin/python

self = <tests.integration.test_memory.TestMemoryCache object at 0x7f5f585830b0>

    def test_response_no_duplicate_read(self):
        """Ensure that response data is read only once per request, whether it's cached or not"""
        session = self.init_session()
        storage_class = type(session.cache.responses)
    
        # Patch storage class to track number of times getitem is called, without changing behavior
        with patch.object(
            storage_class, '__getitem__', side_effect=lambda k: CachedResponse()
        ) as getitem:
            session.get(httpbin('get'))
>           assert getitem.call_count == 1
E           AssertionError: assert 2 == 1
E            +  where 2 = <MagicMock name='__getitem__' id='140047397921200'>.call_count

tests/integration/base_cache_test.py:109: AssertionError
----------------------------- Captured stdout call -----------------------------
                 INFO     Clearing all items from the cache          base.py:100
------------------------------ Captured log call -------------------------------
INFO     requests_cache.backends.base:base.py:100 Clearing all items from the cache
____________ TestSQLiteCache.test_concurrency[2-ThreadPoolExecutor] ____________
[gw0] linux -- Python 3.12.0 /home/runner/work/requests-cache/requests-cache/.venv/bin/python

self = <tests.integration.test_sqlite.TestSQLiteCache object at 0x7f5f587b51c0>
iteration = 2
executor_class = <class 'concurrent.futures.thread.ThreadPoolExecutor'>

    @pytest.mark.parametrize('executor_class', [ThreadPoolExecutor, ProcessPoolExecutor])
    @pytest.mark.parametrize('iteration', range(N_ITERATIONS))
    def test_concurrency(self, iteration, executor_class):
        """Run multithreaded and multiprocess stress tests for each backend.
        The number of workers (thread/processes), iterations, and requests per iteration can be
        increased via the `STRESS_TEST_MULTIPLIER` environment variable.
        """
        start = time()
        url = httpbin('anything')
    
        # For multithreading, we can share a session object, but we can't for multiprocessing
        session = self.init_session(clear=True, expire_after=1)
        if executor_class is ProcessPoolExecutor:
            session = None
        session_factory = partial(self.init_session, clear=False, expire_after=1)
    
        request_func = partial(_send_request, session, session_factory, url)
        with executor_class(max_workers=N_WORKERS) as executor:
>           _ = list(executor.map(request_func, range(N_REQUESTS_PER_ITERATION)))

tests/integration/base_cache_test.py:372: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/opt/hostedtoolcache/Python/3.12.0-beta.3/x64/lib/python3.12/concurrent/futures/_base.py:619: in result_iterator
    yield _result_or_cancel(fs.pop())
/opt/hostedtoolcache/Python/3.12.0-beta.3/x64/lib/python3.12/concurrent/futures/_base.py:317: in _result_or_cancel
    return fut.result(timeout)
/opt/hostedtoolcache/Python/3.12.0-beta.3/x64/lib/python3.12/concurrent/futures/_base.py:449: in result
    return self.__get_result()
/opt/hostedtoolcache/Python/3.12.0-beta.3/x64/lib/python3.12/concurrent/futures/_base.py:401: in __get_result
    raise self._exception
/opt/hostedtoolcache/Python/3.12.0-beta.3/x64/lib/python3.12/concurrent/futures/thread.py:58: in run
    result = self.fn(*self.args, **self.kwargs)
tests/integration/base_cache_test.py:400: in _send_request
    return session.get(url, params={f'key_{i}': f'value_{i}'})
requests_cache/session.py:103: in get
    return self.request('GET', url, params=params, **kwargs)
requests_cache/session.py:159: in request
    return super().request(method, url, *args, headers=headers, **kwargs)  # type: ignore
.venv/lib/python3.12/site-packages/requests/sessions.py:589: in request
    resp = self.send(prep, **send_kwargs)
requests_cache/session.py:194: in send
    cached_response = self.cache.get_response(actions.cache_key)
requests_cache/backends/base.py:68: in get_response
    response = self.responses.get(key)
<frozen _collections_abc>:807: in get
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <requests_cache.backends.sqlite.SQLiteDict object at 0x7f5f52247a40>
key = 'a8d791895d0b043c'

    def __getitem__(self, key):
        with self.connection() as con:
>           cur = con.execute(f'SELECT value FROM {self.table_name} WHERE key=?', (key,))
E           sqlite3.InterfaceError: bad parameter or other API misuse

requests_cache/backends/sqlite.py:290: InterfaceError

Warnings

DeprecationWarning: datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.now(datetime.UTC).

[severinsimmler]

This might be related: python/cpython#118172