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/tests.yml

@@ -40,14 +40,14 @@ jobs:
     # @link https://github.com/marketplace/actions/install-php-dependencies-with-composer
     - name: "Install Composer dependencies (PHP < 8.4)"
       if: ${{ matrix.php-versions < '8.4' }}
-      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")
 
     - name: "Install Composer dependencies (PHP 8.4)"
       if: ${{ matrix.php-versions >= '8.4' }}
-      uses: "ramsey/composer-install@v2"
+      uses: "ramsey/composer-install@v3"
       with:
         composer-options: --ignore-platform-reqs
         custom-cache-suffix: $(date -u "+%Y-%m")