feat!: bump celery and drop python 3.5

[gabor-boros]

Description

This PR removes Celery<5 pin from requirements, so resolves a dependency conflict in openedx/edx-platform#29046.

Supporting information

For more information, please see the linked PR.

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[codecov]

Codecov Report

Merging #199 (530161a) into master (fbaa4b8) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #199   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines          412       412           
  Branches        64        64           
=========================================
  Hits           412       412           

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
user_tasks/__init__.py	100.00% <100.00%> (ø)

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[gabor-boros]

@awais786 Thank you for the review! Please not that it would require a release as well to profit get unblocked on Celery side.

[openedx-webhooks]

@gabor-boros 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.

[iamsobanjaved]

@gabor-boros I have merged this PR and also released the new version.

[gabor-boros]

Thank you @iamsobanjaved! We are one step closer

[natabene]

@gabor-boros Thank you for your contribution. @iamsobanjaved Thanks for reviewing and merging!