update composer to v2 in CI

Author: petrparolek

.github/workflows/main.yaml

@@ -13,8 +13,8 @@ on:
 env:
   extensions: "json"
   cache-version: "1"
-  composer-version: "v1"
-  composer-install: "composer update --no-interaction --no-progress --no-suggest --prefer-dist --prefer-stable"
+  composer-version: "v2"
+  composer-install: "composer update --no-interaction --no-progress --prefer-dist --prefer-stable"
   coverage: "none"
 
 jobs: