GH Actions: Bump ramsey/composer-install from 2 to 3

Bumps [ramsey/composer-install](https://github.com/ramsey/composer-install) from 2 to 3.
- [Release notes](https://github.com/ramsey/composer-install/releases)
- [Commits](ramsey/composer-install@v2...v3)

---
updated-dependencies:
- dependency-name: ramsey/composer-install
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/qa.yml

@@ -42,7 +42,7 @@ jobs:
       # Verify the package can be installed succesfully.
       # @link https://github.com/marketplace/actions/install-php-dependencies-with-composer
       - name: Install Composer dependencies
-        uses: ramsey/composer-install@v2
+        uses: ramsey/composer-install@v3
         with:
           # Bust the cache at least once a month - output format: YYYY-MM.
           custom-cache-suffix: $(date -u "+%Y-%m")