Refactor: extract PR title and body into variables

Co-authored-by: woodruffw <[email protected]>

Author: Copilot

.github/workflows/pin-requirements.yml

@@ -134,13 +134,17 @@ jobs:
           GH_TOKEN: ${{ github.token }}
         run: |
           # Try to create a new PR, or update if it already exists
+          # NOTE: Branch deletion after merge is handled by repository settings
+          PR_TITLE="Update pinned requirements for ${SIGSTORE_RELEASE_TAG}"
+          PR_BODY="Pins dependencies for <https://github.com/sigstore/sigstore-python/releases/tag/${SIGSTORE_RELEASE_TAG}>."
+          
           if ! gh pr create \
-            --title "Update pinned requirements for ${SIGSTORE_RELEASE_TAG}" \
-            --body "Pins dependencies for <https://github.com/sigstore/sigstore-python/releases/tag/${SIGSTORE_RELEASE_TAG}>." \
+            --title "${PR_TITLE}" \
+            --body "${PR_BODY}" \
             --base main \
             --head "${SIGSTORE_PIN_REQUIREMENTS_BRANCH}"; then
             # PR already exists, update it
             gh pr edit "${SIGSTORE_PIN_REQUIREMENTS_BRANCH}" \
-              --title "Update pinned requirements for ${SIGSTORE_RELEASE_TAG}" \
-              --body "Pins dependencies for <https://github.com/sigstore/sigstore-python/releases/tag/${SIGSTORE_RELEASE_TAG}>."
+              --title "${PR_TITLE}" \
+              --body "${PR_BODY}"
           fi