Update method for storing commit messages in GitHub Actions

We simplified the way commit messages are stored in the GitHub Action for the PHP workflow. Now, instead of echoing the messages to the environment file line by line, we assign them directly to the "COMMIT_MESSAGES" variable in a single line.

.github/workflows/php.yml

@@ -125,9 +125,7 @@ jobs:
         if: github.ref == 'refs/heads/main' && steps.rector.outcome == 'success'
         run: |
           COMMIT_MESSAGES=$(git log $LATEST_TAG..HEAD --pretty=format:"%h - %s")
-          echo "COMMIT_MESSAGES<<EOF" >> $GITHUB_ENV
-          echo "$COMMIT_MESSAGES" >> $GITHUB_ENV
-          echo "EOF" >> $GITHUB_ENV
+          echo "COMMIT_MESSAGES=$COMMIT_MESSAGES" >> $GITHUB_ENV
 
       - name: Create release
         id: create_release