Add PHPStan to CI

.gitlab-ci.yml

@@ -43,11 +43,10 @@ test:cgl:
     - composer install --prefer-dist --no-progress
     - ./vendor/bin/ecs check --no-progress-bar --clear-cache --fix
 
-# Disabled due to high memory consumption in CI
-# test:phpstan:
-#   image: php:7.3-alpine
-#   stage: test
-#   before_script:
-#   script:
-#     - composer install --prefer-dist --no-progress
-#     - ./vendor/bin/phpstan
+test:phpstan:
+  image: php:7.3-alpine
+  stage: test
+  before_script:
+  script:
+    - composer install --prefer-dist --no-progress
+    - php -d memory_limit=-1 ./vendor/bin/phpstan --no-progress