Fix broken --help flag

Currently, `allowUnknownFlags: false` is commented out, which is not
ideal, because the error message the user gets when using an unknown
flag is pretty confusing:

```
$ chalk --foobar
Input required
```

The actual problem is in meow (see meow#197), but it's been taking a
while to come up with a proper fix for that (see meow#198), so I suggest
using this workaround in the meantime.

See: chalk#32, chalk#33, chalk#39, meow#197, meow#198

cli.js

@@ -52,9 +52,12 @@ const cli = meow(`
  $ echo 'Unicorns from stdin' | chalk --stdin red bold
 `, {
  importMeta: import.meta,
- // TODO: Disabled until https://github.com/sindresorhus/meow/issues/197 is fixed.
- // allowUnknownFlags: false,
+ allowUnknownFlags: false,
  flags: {
+ // TODO: Can be removed when https://github.com/sindresorhus/meow/issues/197 is fixed.
+ help: {type: 'boolean'},
+ version: {type: 'boolean'},
+
  template: {
  type: 'string',
  alias: 't',