Platypush

- [[405](https://git.platypush.tech/platypush/platypush/issues/405)] Fixed
timezone/timestamp rendering issues for `calendar.ical` events.
- [[403](https://git.platypush.tech/platypush/platypush/issues/403)]
Included inherited actions in plugins docs.

- [[384](https://git.platypush.tech/platypush/platypush/issues/384)] Added
`assistant.openai` and `tts.openai` plugins.

- 🐛 Bug fix on one of the entities modules that prevented the application from
loading when `.` is part of `PYTHONPATH`.

- A proper solution for the `utcnow()` issue.

It was a bit trickier than expected to solve, but now Platypush uses a
`utcnow()` facade that always returns a UTC datetime in a timezone-aware
representation.

The code should however also handle the case of timestamps stored on the db in
the old format.

- Fixed regression introduced by
[c18768e61fef62924f4c1fac3089ecfb83666dab](https://git.platypush.tech/platypush/platypush/commit/c18768e61fef62924f4c1fac3089ecfb83666dab).
Python seems to have introduced a breaking change from the version 3.12 -
`datetime.utcnow()` is not deprecated, but `datetime.UTC`, the suggested
alternative, isn't available on older versions of Python. Added a workaround
that makes Platypush compatible with both the implementations.

- [[368](https://git.platypush.tech/platypush/platypush/issues/368)] Added
Ubuntu packages.

- Fixed bug that didn't get hooks to match events imported through the new
`platypush.events` symlinked module.