Fix syntax error in docstring

Update mypy/typeshed, update a few types

This required a recent update to typeshed/mypy.

Fixes #3093

Fixes a conflict between pip-tools and pip.

autoreload: Various updates

This flag terminates the autoreload loop after the first successful
run. This makes it possible to cleanly shut down a process that is using
"python -m tornado.autoreload" without printing a traceback.

Fixes #2398

build(deps): bump certifi from 2022.12.7 to 2023.7.22

Bumps [certifi](https://github.com/certifi/python-certifi) from 2022.12.7 to 2023.7.22.
- [Commits](https://github.com/certifi/python-certifi/compare/2022.12.07...2023.07.22)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: indirect
...
Signed-off-by: Ndependabot[bot] <support@github.com>

A previous commit added support for using autoreload within programs
that were started as directories; this commit supports them when
run with the -m tornado.autoreload wrapper.

This change may have side effects for file mode since we now use
runpy.run_path instead of executing the file by hand (I don't think
the run_path function existed when this code was originally written).

This will make it easier to add other options (for #2398)

Running a directory has some but not all of the behavior of
running a module, including setting __spec__, so we must be careful
not to break things by assuming that __spec__ means module mode.

Fixes #2855

build(deps): bump pygments from 2.14.0 to 2.15.0

Bumps [pygments](https://github.com/pygments/pygments) from 2.14.0 to 2.15.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](https://github.com/pygments/pygments/compare/2.14.0...2.15.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: indirect
...
Signed-off-by: Ndependabot[bot] <support@github.com>

asyncio: Remove atexit hook

This hook was added because of an only-in-CI issue, but we have since
improved our cleanup of the selector thread. As long as this passes
CI, I think we can remove the atexit hook.

Fixes #3291

auth: Various updates

Matches a change made to the Google auth mixin in a previous commit.

Fixes #756

The read_stream scope was replaced with user_posts; this change
was made to demos/facebook/facebook.py in #1674 but the corresponding
comment was not updated. The offline_access scope has also been removed
but seems irrelvant to this comment.

Fixes #1566

Add some more detail to app registration docs.

This was done mainly to verify that we don't need to introduce
new parameters as requested in #2140

Closes #2140

It's unclear to what extent this class still works given Twitter's
recent API changes. Deprecate it since I don't intend to track
future changes here.

OAuth2Mixin.authorize_redirect has never used this argument
and similar methods in this module don't have it.

Closes #1122

test: Add test for open redirect fixed in 6.3.2

Updates for Python 3.12

Python 3.12 deprecates the utcnow and utcfromtimestamp methods and
discourages the use of naive datetimes to represent UTC. This was
previously the main way that Tornado used datetimes (since it was
the only option available in Python 2 before the introduction
of datetime.timezone.utc in Python 3.2).

- httpclient_test: Test-only change to test that both kinds of datetimes
  are supported in If-Modified-Since (this just calls
  httputil.format_timestamp)
- httputil: No functional changes, but format_timestamp's
  support for both naive and aware datetimes is now tested.
- locale: format_timestamp now supports aware datetimes (in
  addition to the existing support for naive datetimes).
- web: Cookie expirations internally use aware datetimes.
  StaticFileHandler.get_modified_time now supports both and the
  standard implementation returns aware.

It feels fragile that "naive" and "aware" datetimes are not distinct
types but subject to data-dependent behavior. This change uses
"aware" datetimes throughout Tornado, but some operations (comparisons
and subtraction) fail with mixed datetime types and if I missed any
in this change may cause errors if naive datetimes were used (where
previously naive datetimes would have been required). But that's
apparently the API we have to work with.

Now that python/cpython#105808 is fixed in beta 3.

asyncio_test: Use inequality when looking for thread leaks

Sometimes we have a net reduction in the thread count
because there was an extra thread running at the time captured
the starting count, so use inequality instead of exact matches.

asyncio: Modernize type annotations