Upgrade to composer/composer v2

Author: szepeviktor

.travis.yml

@@ -21,7 +21,7 @@ before_install:
   - "composer validate --strict"
 
 install:
-  - "composer update --no-interaction --no-suggest"
+  - "composer update --no-interaction"
 
 script:
   - "composer test:syntax -- --no-progress"

composer.json

@@ -17,7 +17,7 @@
         "symfony/polyfill-php73": "^1.12.0"
     },
     "require-dev": {
-        "composer/composer": "^1.10.23",
+        "composer/composer": "^2.1.12",
         "dealerdirect/phpcodesniffer-composer-installer": "^0.7",
         "php-parallel-lint/php-parallel-lint": "^1.1",
         "phpstan/phpstan-strict-rules": "^1.0",