Xmltotabular

Maintenance release

* Adds explicit support for Python 3.10
* Switch to a fork of the GitHub Actions `pre-commit` action (`pre-commit/action` is broken on windows runners)
* Minor code and dependency linting

Features

* Support for multiple root entities per XML doc, e.g.

<records>
<record />
<record />
<record />
...
</records>


Housekeeping
* Better logging/output messages
* Exposes `xmltotabular.__version__` and `xmltotabular.__version_info__`
* Greatly expanded test suite (though more still required)

Minor bugfix release.

Changes to the public API:
* `XMLCollectionToTabular` accepts `sqlite-max-vars` (defaults to 999)
* `XMLCollectionToTabular` accepts `check_doctype` (defaults to `False` -- previously this behaviour was *enabled* by default)

Other changes:
* SQLite backend now defaults to [`locking_mode = EXCLUSIVE`](https://www.sqlite.org/pragma.html#pragma_locking_mode)