[ci] use composer 2.2 for Symfony 4.4 compat

Author: jrushlow

.github/workflows/ci.yaml

@@ -136,7 +136,7 @@ jobs:
               with:
                   coverage: "none"
                   php-version: ${{ matrix.php-version }}
-                  tools: composer:v2
+                  tools: composer:v2.2
 
             - name: "Add PHPUnit matcher"
               run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"