Increase Django max version to 4.1

[spenserblack]

Description

I'm intending to use this on a Django 4.1 project, so I wanted to increase the maximum Django version to 4.1 and add 4.1 to the tested versions. There aren't any code changes.

There may be more work to do, but I wanted this PR to at least get things started. Not a draft in case this PR is good-to-go as is.

4.0's active support has ended, and its security support will end in <6 months.

Checklist

• I have ran tox to ensure tests pass
• Usage documentation added in case of new features
• README & CHANGELOG updated
• Tests added / I have not lowered coverage from 100%

[codecov]

Codecov Report

Merging #76 (adb8e4e) into main (aefb860) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main       #76   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          133       133           
  Branches        27        27           
=========================================
  Hits           133       133           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[marksweb]

@spenserblack Thanks 👍