build: Update dependencies to modern versions

[marksweb]

Description

This drops support for old python/django/django-cms versions.

Checklist

• I have opened this pull request against master
• I have added or modified the tests when changing logic
• I have followed the conventional commits guidelines to add meaningful information into the changelog
• 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]

Codecov Report

Merging #43 (97f6b4b) into master (2cb4ffa) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #43   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         8    +1     
  Lines          117       123    +6     
  Branches        19        20    +1     
=========================================
+ Hits           117       123    +6     

Impacted Files	Coverage Δ
djangocms_icon/models.py	100.00% <ø> (ø)
djangocms_icon/apps.py	100.00% <100.00%> (ø)
djangocms_icon/cms_plugins.py	100.00% <100.00%> (ø)

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