Use --parallel flag when mutation testing

Author: SebKay

composer.json

@@ -75,7 +75,7 @@
             "XDEBUG_MODE=coverage ./vendor/bin/pest --parallel --stop-on-failure --coverage --min=85"
         ],
         "test:mutations": [
-            "XDEBUG_MODE=coverage ./vendor/bin/pest --mutate"
+            "XDEBUG_MODE=coverage ./vendor/bin/pest --parallel --mutate"
         ],
         "assets:build": [
             "bun install",