Neoteroi-mkdocs

- Show event description in Gantt diagrams, by changbowen
- Add possibility to configure months time format in Gantt diagrams, by yasamoka

- Unpins the dependencies on `mkdocs` and `httpx`, to fix [42](https://github.com/Neoteroi/mkdocs-plugins/issues/42).

Thanks to joseale2310 for reporting the issue.

- Adds support for icons in cards, by Andy2003.
- Adds support for anchors with target="_blank" in cards.

- Fixes detail in the `contribs` plugin: when the name is specified for a
contributor by email address, it is used.
- Improves `pyproject.toml`.
- Adds `py.typed` files.

- Improves the `contribs` plugin, adding the possibility to document
contributors for a page also using `.txt` files close to `.md` files. This
can be useful in several cases:
- - To document contributors who worked outside of Git, for example when providing
pictures for the page, or written content provided to someone who is
adding content to the MkDocs site.
- - To document contributors following a Git history re-write
- Improves the `contribs` plugin, adding the possibility to exclude files by
glob patterns (fix 33).
- Improves the `contribs` plugin, adding the possibility to merge contributors
by name, for scenarios when the same person commits using different names
(Git reports different contributors in such cases) and it is preferred
displaying information aggregated as single contributor.

- Adds the possibility to specify a `class` for the root HTML element of `cards`.
- Fixes a bug in the `contribs` plugin (adds a carriage return before the contribution fragment).
- Modifies the packages to group all extensions under `neoteroi.mkdocs` namespace.
- Replaces `setup.py` with `pyproject.toml`.