ci: Fix tests and add pre-commit

[marksweb]

Description

This addresses issues with tests and adds pre-commit config for linting & basic checks to hopefully prevent the linter workflow failing on PRs.

Checklist

• [x] I have opened this pull request against master
• [ ] I have added or modified the tests when changing logic
• [x] I have followed the conventional commits guidelines to add meaningful information into the changelog
• [x] I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.

[codecov[bot]]

Codecov Report

Merging #1306 (0c94147) into master (6a4706d) will increase coverage by 0.02%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1306      +/-   ##
==========================================
+ Coverage   72.18%   72.21%   +0.02%     
==========================================
  Files          72       72              
  Lines        3236     3239       +3     
  Branches      559      563       +4     
==========================================
+ Hits         2336     2339       +3     
  Misses        734      734              
  Partials      166      166              

Impacted Files	Coverage Δ
filer/urls.py	100.00% <ø> (ø)
filer/admin/folderadmin.py	71.82% <100.00%> (ø)
filer/thumbnail_processors.py	38.46% <100.00%> (ø)
filer/utils/compatibility.py	59.09% <100.00%> (ø)
filer/utils/files.py	69.87% <100.00%> (ø)
filer/admin/views.py	65.71% <0.00%> (+1.53%)	:arrow_up:

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[marksweb]

I didn't know about pre-commit and will apply that to my other projects

@jrief It's a very neat tool for improving a workflow & catching issues before you get to a PR & workflows - especially linters.