Generic views: handle undefined date facet fields values

This resolves a regression introduced in django-haystack#1690.

Merge pull request django-haystack#1848 from django-haystack/pre-comm…

…it-ci-update-config

[pre-commit.ci] pre-commit autoupdate

Merge pull request django-haystack#1838 from claudep/remove35

Remove support for Python 3.5

Restore convenience import for haystack.utils.highlighter

Merge pull request django-haystack#1775 from dulmandakh/publish

Publish to PyPI on Github release

Create codeql-analysis.yml

Merge pull request django-haystack#1727 from amites/patch-1

doc update -- fixes broken link

Merge pull request django-haystack#1721 from fakhar362/issues/default…

…-alias

Fixed hardcoded default connection alias

Merge pull request django-haystack#1596 from klass-ivan/collecting-de…

…ep-attr-through-m2m

Fixed collection of deep attributes through m2m relation

Optimize ElasticSearch backend (closes django-haystack#1590)

Thanks to @klass-ivan for the patch