Support Django 4.1, Python 3.10, and fix Selenium tests

[adamchainz]

1. Add Django 4.1 to the test matrix
2. Add Python 3.10 to the test matrix
3. Deal with some deprecation warnings from running the tests on Django 4.0+
4. Update Selenium method calls for removals in Selenium 4.3.0 of find_element[s]_by_* methods, to the new find_element[s] method with By argument (docs).

[adamchainz]

I managed to run the tests locally with the latest Chrome + chromedriver, pending approval to run on GitHub Actions.

[codecov]

Codecov Report

Merging #154 (8c09928) into master (68a87ba) will decrease coverage by 0.74%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #154      +/-   ##
==========================================
- Coverage   99.60%   98.86%   -0.75%     
==========================================
  Files           7        7              
  Lines         254      264      +10     
==========================================
+ Hits          253      261       +8     
- Misses          1        3       +2     

Impacted Files	Coverage Δ
django_select2/__init__.py	66.66% <0.00%> (-33.34%)	⬇️
django_select2/forms.py	99.47% <0.00%> (-0.53%)	⬇️
django_select2/conf.py	100.00% <0.00%> (ø)

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[codingjoe]

Thanks, @adamchainz, appreciate the help 👍
I'll invest some time to update some other things on the CI suite today. I'll ship a new release before the weekend 😃