Fix versioning job: replace expired PAT with GitHub App token

[anth-volk]

Fixes #3331

Summary

• Replace secrets.POLICYENGINE_GITHUB (expired PAT) with actions/create-github-app-token@v1 in the versioning job
• Matches the pattern used in policyengine-us and policyengine-api-v2-alpha

Test plan

• Merge this PR and confirm the versioning job succeeds (creates the "Update PolicyEngine API" commit)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.20%. Comparing base (55a193a) to head (3fa9631).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3332   +/-   ##
=======================================
  Coverage   72.20%   72.20%           
=======================================
  Files          56       56           
  Lines        2425     2425           
  Branches      423      423           
=======================================
  Hits         1751     1751           
  Misses        595      595           
  Partials       79       79           

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