Switch to zoneinfo from pytz

[matmair]

We target 3.9 which has zoneinfo for timezone info instead of pytz.

[netlify]

✅ Deploy Preview for inventree-web-pui-preview canceled.

Name	Link
🔨 Latest commit	3e7a3b6
🔍 Latest deploy log	https://app.netlify.com/sites/inventree-web-pui-preview/deploys/66a95a21ec85070008da3a80

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.

Project coverage is 84.25%. Comparing base (637a7fe) to head (3e7a3b6).
Report is 9 commits behind head on master.

Files	Patch %	Lines
src/backend/InvenTree/InvenTree/helpers.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7645      +/-   ##
==========================================
+ Coverage   83.52%   84.25%   +0.72%     
==========================================
  Files        1114     1105       -9     
  Lines       49355    48854     -501     
  Branches     1571     1440     -131     
==========================================
- Hits        41225    41162      -63     
+ Misses       7734     7314     -420     
+ Partials      396      378      -18     

Flag	Coverage Δ
backend	85.33% <77.77%> (-0.03%)	⬇️

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[SchrodingersGat]

Nice. Should we also remove pytz from the requirements?

[matmair]

@SchrodingersGat sadly not, some of our dependencies still depend on it

[matmair]

I need to figure out why CI works on my machine but not on GH

[matmair]

This is more complex than initially thought. https://blog.ganssle.io/articles/2018/03/pytz-fastest-footgun.html
I am amazed we have not had problems with pytz before.

[SchrodingersGat]

Wow, what a deep dive!