fix: add support of django 4.0

[jbpenrath]

Description

django-cms 3.11 adds the support of django 4.0 but currently djangocms-link is not compatible with this version of django as there is use of force_text in the codebase. So we remove the use of this deprecated method in favor of force_str.

Related resources

• https://github.com/django-cms/django-cms/blob/release/3.11.x/CHANGELOG.rst#highlights
• https://docs.djangoproject.com/en/4.0/releases/4.0/#features-removed-in-4-0

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 #203 (6b40481) into master (3afb7e4) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #203   +/-   ##
=======================================
  Coverage   93.54%   93.54%           
=======================================
  Files          22       22           
  Lines         279      279           
  Branches       53       53           
=======================================
  Hits          261      261           
  Misses         11       11           
  Partials        7        7           

Impacted Files	Coverage Δ
djangocms_link/models.py	94.73% <100.00%> (ø)

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[vinitkumar]

Thanks for your pull request @jbpenrath. I see a couple of things missing from your PR. It would be wonderful if you can add those too.

These needs to be updated: https://github.com/django-cms/djangocms-link/blob/master/.github/workflows/test.yml#L17

Please add a requirements file for django4.0 as well and add their reference in the test.yml so that the CI also tests it against those version.