update artifacts GitHub actions to v4 (#89)

## Motivation
GitHub is currently phasing out support for `actions/upload-artifact`
and `actions/download-artifact` versions other than the latest major
release v4:
https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/

> Starting December 5, 2024, GitHub Actions customers will no longer be
able to use v3 of
[actions/upload-artifact](https://github.com/actions/upload-artifact) or
[actions/download-artifact](https://github.com/actions/download-artifact).

This PR updates the the action to v4.

## Changes
Update the GitHub artifact action versions to v4 before the burn-down.

.github/workflows/test-appsync-utils.yml

@@ -66,7 +66,7 @@ jobs:
           localstack logs | gzip > logs.txt.gz
       - name: Upload the logs as an artifact
         if: success() || failure()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ls-logs-${{ github.run_number }}
           path: |