Fix "Bump version" workflow: replace broken ad-m/github-push-action with direct git push

[Copilot]

ad-m/github-push-action@master constructs an invalid git refspec at runtime (src refspec @github.com/softwaremmm/gatekeeper_pipeline.git does not match any), causing the push step to fail with exit code 1.

Changes

• .github/workflows/bump.yml: Replace the broken third-party action with a direct git push, passing PAT_TOKEN via env rather than inline interpolation for proper secret masking:

- name: push changes
  env:
    PAT_TOKEN: ${{ secrets.PAT_TOKEN }}
  run: |
    git remote set-url origin "https://oauth2:${PAT_TOKEN}@github.com/${{ github.repository }}.git"
    git push origin develop --tags