Bump ramsey/composer-install from 2 to 3 (#20)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/phpstan.yml

@@ -20,7 +20,7 @@ jobs:
           coverage: none
 
       - name: Install composer dependencies
-        uses: ramsey/composer-install@v2
+        uses: ramsey/composer-install@v3
 
       - name: Run PHPStan
         run: ./vendor/bin/phpstan --error-format=github