[Actions] Downgrade Composer to v1

- The current fxp/composer-asset-plugin version we use is incompatible with Composer v2

.github/workflows/php.yml

@@ -37,7 +37,7 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-versions }}
-          tools: pecl
+          tools: pecl, composer:v1
           extensions: pdo_mysql, gd, zip, opcache, ctype, pcntl, ldap, apcu, memcached, redis, imagick, memcache
           coverage: xdebug
           ini-values: apc.enabled=1, apc.enable_cli=1