chore: added Django 5.2 tox and CI compatibility checks

[vgulati-apphelix]

Description:
Adds Django 5.2 to the project’s tox and CI build matrix, and bumps the package version/changelog to reflect the change.

Changes:
Extend tox test matrix to include a Django 5.2 environment.
Extend GitHub Actions CI to run the added Django 5.2 tox environment.
Bump package version to 3.0.6 and add a changelog entry.
Private JIRA Link:
BOMS-407

Merge checklist:

• Any new requirements are in the right place (do not manually modify the requirements/*.txt files)
  • base.in if needed in production but edx-analytics-data-api doesn't install it
  • test-master.in if edx-analytics-data-api pins it, with a matching version
  • make upgrade && make requirements have been run to regenerate requirements
• Version bumped
• Changelog record added

Post merge:

• Tag pushed and a new version released
  • Note: Assets will be added automatically. You just need to provide a tag (should match your version number) and title and description.
• After versioned build finishes in Travis, verify version has been pushed to PyPI
  • Each step in the release build has a condition flag that checks if the rest of the steps are done and if so will deploy to PyPi.
    (so basically once your build finishes, after maybe a minute you should see the new version in PyPi automatically (on refresh))
• PR created in edx-analytics-data-api to upgrade dependencies (including edx-enterprise-data)
  • This must be done after the version is visible in PyPi as make upgrade in edx-analytics-data-api will look for the latest version in PyPi.
  • Note: the edx-enterprise-data constraint in edx-analytics-data-api must also be bumped to the latest version in PyPi.