Fix pre-commit workflow error when writing multiline string

Error message:
    Error: Unable to process file command 'output' successfully.
    Error: Invalid format 'index cd0e971..e9a93b2 100644'

Author: zachborboa

.github/workflows/pre-commit-auto-update.yml

@@ -26,7 +26,10 @@ jobs:
         run: |
           git diff --color
           changes="$(git diff)"
-          echo "changes=${changes}" >> $GITHUB_OUTPUT
+          delimiter="$(openssl rand -hex 8)"
+          echo "changes<<${delimiter}" >> "${GITHUB_OUTPUT}"
+          echo "${changes}" >> "${GITHUB_OUTPUT}"
+          echo "${delimiter}" >> "${GITHUB_OUTPUT}"
 
       - name: Create pull request
         uses: peter-evans/create-pull-request@v5