You can run level 8

ondrejmirtes · ondrejmirtes · commit 32bfb1453358 · 2019-12-14T21:39:33.000+01:00
diff --git a/phpstan.neon b/phpstan.neon
@@ -2,6 +2,6 @@ includes:
 	- vendor/phpstan/phpstan-strict-rules/rules.neon
 	- vendor/phpstan/phpstan-deprecation-rules/rules.neon
 parameters:
-	level: 7
+	level: 8
 	checkGenericClassInNonGenericObjectType: false
 	checkMissingIterableValueType: false
