Drop phpstan ignore error missingType.generics.

For some reason this was needed in the past, but no longer is.
Possibly due to changes in phpstan or in composer packages.

Author: donquixote

phpstan.neon

@@ -14,4 +14,3 @@ parameters:
     - "#^Unsafe usage of new static\\(\\).$#"
     # Allow to omit `<mixed>` as iterable or generic type qualifier.
     - identifier: missingType.iterableValue
-    - identifier: missingType.generics