Refactor version extraction in PR title update workflow for improved …

…accuracy

Co-authored-by: Nicola Soranzo <nicola.soranzo@earlham.ac.uk>

.github/workflows/pr-title-update.yml

@@ -19,11 +19,10 @@ jobs:
           PR_TITLE: "${{ github.event.pull_request.title }}"
           REPO: "${{ github.repository }}"
         run: |
-          VERSION=$(echo $TARGET_BRANCH | grep -oP 'release_\K.*' || true)
+          VERSION=$(echo $TARGET_BRANCH | grep -oP '^release_\K\d+.\d+$' || true)
+          NEW_TITLE=$(echo "$PR_TITLE" | sed -E "s/\[[0-9]+\.[0-9]+\] //")
           if [[ -n "$VERSION" ]]; then
-            NEW_TITLE="[$VERSION] ${PR_TITLE#*\] }"
-          else
-            NEW_TITLE="${PR_TITLE#*\] }"
+            NEW_TITLE="[$VERSION] $NEW_TITLE"
           fi
           if [[ "$NEW_TITLE" != "$PR_TITLE" ]]; then
             gh pr edit $PR_NUMBER --repo "$REPO" --title "$NEW_TITLE"