ci: fix shivammathur/setup-php tool name (php-parallel-lint → parallel-lint)

The 'php-parallel-lint' tool name is not recognised by shivammathur/setup-php@v2;
the canonical name is 'parallel-lint'. This was causing all PHP lint matrix jobs
to fail with 'parallel-lint: command not found'.

Author: jdevalk

.github/workflows/lint-php.yml

@@ -28,7 +28,7 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
-          tools: php-parallel-lint
+          tools: parallel-lint
           coverage: none
 
       - name: Lint PHP files