Bump ramsey/composer-install in the actions group across 1 directory

Bumps the actions group with 1 update in the / directory: [ramsey/composer-install](https://github.com/ramsey/composer-install).


Updates `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-version: '3'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/phpunit.yml

@@ -72,7 +72,7 @@ jobs:
         run: composer config --unset platform.php
 
       - name: Install Composer dependencies
-        uses: ramsey/composer-install@v2
+        uses: ramsey/composer-install@v3
         with:
           dependency-versions: highest
           composer-options: "--prefer-dist --no-progress"