Limit version range for isort to >=5.11.1, <6.0

[foarsitter]

The actions fail because isort beta (6.0.0b2) is installed by default. Version 5.11.0 is missing the colorama dependency so therefore pinning the lower bounds to 5.11.1

[codecov[bot]]

Codecov Report

Merging #234 (0a9f7a7) into master (3eb4a43) will decrease coverage by 0.67%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #234      +/-   ##
==========================================
- Coverage   93.88%   93.22%   -0.67%     
==========================================
  Files          10       11       +1     
  Lines         523      531       +8     
  Branches       66       67       +1     
==========================================
+ Hits          491      495       +4     
- Misses         19       22       +3     
- Partials       13       14       +1     

see 1 file with indirect coverage changes

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more

[claudep]

Excluding some Python versions for Django main should be the object of a different PR.