Update cachetools to 5.2.0

[pyup-bot]

This PR updates cachetools from 4.1.0 to 5.2.0.

Changelog

5.2.0

===================

- Add ``cachetools.keys.methodkey()``.

- Add ``cache_clear()`` function to decorators.

- Add ``src`` directory to ``sys.path`` for Sphinx autodoc.

- Modernize ``func`` wrappers.

5.1.0

===================

- Add cache decorator parameters as wrapper function attributes.

5.0.0

===================

- Require Python 3.7 or later (breaking change).

- Remove deprecated submodules (breaking change).

The ``cache``, ``fifo``, ``lfu``, ``lru``, ``mru``, ``rr`` and
``ttl`` submodules have been deleted.  Therefore, statements like

``from cachetools.ttl import TTLCache``

will no longer work. Use

``from cachetools import TTLCache``

instead.

- Pass ``self`` to ``cachedmethod`` key function (breaking change).

The ``key`` function passed to the ``cachedmethod`` decorator is
now called as ``key(self, *args, **kwargs)``.

The default key function has been changed to ignore its first
argument, so this should only affect applications using custom key
functions with the ``cachedmethod`` decorator.

- Change exact time of expiration in ``TTLCache`` (breaking change).

``TTLCache`` items now get expired if their expiration time is less
than *or equal to* ``timer()``.  For applications using the default
``timer()``, this should be barely noticable, but it may affect the
use of custom timers with larger tick intervals.  Note that this
also implies that a ``TTLCache`` with ``ttl=0`` can no longer hold
any items, since they will expire immediately.

- Change ``Cache.__repr__()`` format (breaking change).

String representations of cache instances now use a more compact and
efficient format, e.g.

``LRUCache({1: 1, 2: 2}, maxsize=10, currsize=2)``

- Add TLRU cache implementation.

- Documentation improvements.

4.2.4

===================

- Add submodule shims for backward compatibility.

4.2.3

===================

- Add documentation and tests for using ``TTLCache`` with
``datetime``.

- Link to typeshed typing stubs.

- Flatten package file hierarchy.

4.2.2

===================

- Update build environment.

- Remove Python 2 remnants.

- Format code with Black.

4.2.1

===================

- Handle ``__missing__()`` not storing cache items.

- Clean up ``__missing__()`` example.

4.2.0

===================

- Add FIFO cache implementation.

- Add MRU cache implementation.

- Improve behavior of decorators in case of race conditions.

- Improve documentation regarding mutability of caches values and use
of key functions with decorators.

- Officially support Python 3.9.

4.1.1

===================

- Improve ``popitem()`` exception context handling.

- Replace ``float('inf')`` with ``math.inf``.

- Improve "envkey" documentation example.

Links

• PyPI: https://pypi.org/project/cachetools
• Changelog: https://pyup.io/changelogs/cachetools/
• Repo: https://github.com/tkem/cachetools/