Plemmy

Changes outlined in PR https://github.com/tjkessler/plemmy/pull/23.

Thanks to JLukeBlakey for the fix!

Outlined in PR https://github.com/tjkessler/plemmy/pull/21, this change adds the `get_communities` method to the `LemmyHttp` object. For example:

python
from plemmy import LemmyHttp

srv = LemmyHttp("<lemmy server>")
api_response = srv.get_communities(type_="All", sort="Hot", page=0, limit=50)


Thanks to gwbischof for the contribution!

Per PR https://github.com/tjkessler/plemmy/pull/20 and issue https://github.com/tjkessler/plemmy/issues/19, Plemmy can be installed on Python 3.7+ (previously set to 3.11). This has been updated in `pyproject.toml`.

Thanks to gwbischof for highlighting this, and to ihyoudou for finding the minimum required Python version.

Per issue https://github.com/tjkessler/plemmy/issues/17, `block_community` did not work as of Plemmy version `0.3.4`. I've tracked down the cause: it looks like the changes made in PR https://github.com/tjkessler/plemmy/pull/15 to the `create_form` utility function, i.e., turning boolean variables into strings, only really applies to `get_person_mentions`, as other functions such as `block_community` actually _do_ require a boolean data type.

mike-fmh: I had to revert some changes you made, but I think my solution of manually converting the boolean to a string fixes the `get_person_mentions` function. Not sure how many other similar functions are affected, feel free to make similar changes and make a PR if you run into any issues.

Very unfortunate that the API has some datatype mismatching, hopefully this will be fixed in the future.

Thanks to AndrewFlan for pointing me in the right direction!

No functional changes, but:

- Build/installation now utilizes `pyproject.toml` instead of the deprecated `setup.py`
- Added a [GitHub workflow](https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python) to publish Plemmy to PyPI whenever a new release is published
- Version: `0.3.3 -> 0.3.4`
- Added a GitHub workflow to run unit tests with `pytest` on new PRs
- Added a unit test to test package import

Per the issue found in PR https://github.com/tjkessler/plemmy/pull/15, boolean values need to be sent as strings to Lemmy. This change affects all boolean values sent to Lemmy. Thanks to mike-fmh for the contribution!