ci: simplify syntax check

Author: dannyvankooten

composer.json

@@ -37,7 +37,7 @@
             "@static-analysis",
             "@test"
         ],
-        "check-syntax": "find . -name '*.php' -not -path './vendor/*' -not -path './node_modules/*' -print0 | xargs -0 -n1 php -l",
+        "check-syntax": "find . -path ./vendor -prune -o -type f -name '*.php' -print0 | xargs -0 -n1 -P4 php --define error_reporting=-1 -l -n | (! grep -v \"No syntax errors detected\" )",
         "check-codestyle": "vendor/bin/phpcs -sn",
         "check-plugin": "wp plugin check boxzilla --mode=update --ignore-warnings --ignore-codes=hidden_files,application_detected,plugin_updater_detected",
         "static-analysis": "vendor/bin/phpstan analyse",