Bump codecov-action to v4

Part of the NodeJS 16 to NodeJS 20 migration:
https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/

Author: stronk7

.github/workflows/phpcs.yml

@@ -96,7 +96,7 @@ jobs:
 
       - name: Upload coverage
         if: ${{ !cancelled() }}
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: clover.xml