Add support for aggregation pipelines in updates

Modernize project infrastructure

Fix README.rst which prevented PyPI upload

Remove deprecated pkg_ressources usage

Silence warning in deploy steps.

Fix deployment authentication.

Advertize that python 3.10 is supported.

Add some documentation on using Mongomock to upgrade Pymongo.

Add default and options to get_default_database() (#693)

Add the `default=` parameter to `MongoClient.get_default_database()` to
equalize behavior with `pymongo`.

Forward remaining keyword arguments from
`MongoClient.get_default_database()` to `MongoClient.get_database()`.

Authored by leorochael

Fix type stubs for patch and test it to prevent regressions.

Fixes #691