Fix jobs/tests/test_models.py misusing assertTrue

[code-review-doctor]

Fixes #1986

[rbanffy]

LGTM

[rbanffy]

Sorry. Not a full-time contributor. At least I had an approve button ;-)

[ambv]

This is a valid fix, and a straightforward change.

[hugovk]

Here's some others, found using https://github.com/isidentical/teyit.

assert_ was removed in 3.12: https://docs.python.org/3/whatsnew/3.12.html#id3

diff --git a/downloads/tests/test_models.py b/downloads/tests/test_models.py
index f27e951..d31afae 100644
--- a/downloads/tests/test_models.py
+++ b/downloads/tests/test_models.py
@@ -82,8 +82,8 @@ class DownloadModelTests(BaseDownloadTests):
 
         release_38 = Release.objects.create(name='Python 3.8.0')
         self.assertFalse(release_38.is_version_at_least_3_9)
-        self.assert_(release_38.is_version_at_least_3_5)
+        self.assertTrue(release_38.is_version_at_least_3_5)
 
         release_310 = Release.objects.create(name='Python 3.10.0')
-        self.assert_(release_310.is_version_at_least_3_9)
-        self.assert_(release_310.is_version_at_least_3_5)
+        self.assertTrue(release_310.is_version_at_least_3_9)
+        self.assertTrue(release_310.is_version_at_least_3_5)