Create GitHub release with changelog on deploy

[phavekes]

Updates .github/workflows/deploy.yml to build a changelog (ardalanamini/auto-changelog) and create a GitHub release (softprops/action-gh-release) on tag pushes, following the OpenConext-Invite deploy workflow.

• Adds contents: write permission to the deployment job
• checkout with fetch-depth: 0 so the changelog has commit history
• Changelog + release steps only run on tag pushes (skipped for workflow_dispatch/snapshot builds)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.27%. Comparing base (4ea0d61) to head (2e81271).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #159      +/-   ##
============================================
- Coverage     94.55%   94.27%   -0.28%     
  Complexity      348      348              
============================================
  Files            59       59              
  Lines          1083     1083              
  Branches         82       82              
============================================
- Hits           1024     1021       -3     
- Misses           32       35       +3     
  Partials         27       27              

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