CI: Write LIST_OPEN_ISSUES as multi-line string to $GITHUB_OUTPUT

Author: andygrunwald

.github/workflows/label-pull-requests-all.yml

@@ -20,7 +20,9 @@ jobs:
       - run: |
           listOpenIssues="$(gh pr list --repo andygrunwald/go-jira --state open --limit 100 --json number --jq '.[].number')"
         
-          echo "LIST_OPEN_ISSUES=$listOpenIssues\n" >> $GITHUB_OUTPUT
+          echo 'LIST_OPEN_ISSUES<<EOF' >> $GITHUB_OUTPUT
+          echo $listOpenIssues >> $GITHUB_OUTPUT
+          echo 'EOF' >> $GITHUB_OUTPUT
         id: find_all_open_prs
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}