Fix phpstan error

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "868318925a34cd137ac3543e10e0ec27",
+    "content-hash": "c2a0a1f997ddde6a4b8ae97b05190f2f",
     "packages": [
         {
             "name": "antoligy/dom-string-iterators",

system/src/Grav/Framework/Relationships/Relationships.php

@@ -184,7 +184,7 @@ class Relationships implements RelationshipsInterface
     /**
      * @param string $name
      * @param array $options
-     * @return ToOneRelationship|ToManyRelationship
+     * @return ToOneRelationship<T,P>|ToManyRelationship<T,P>
      */
     private function createRelationship(string $name, array $options): RelationshipInterface
     {
@@ -203,9 +203,11 @@ class Relationships implements RelationshipsInterface
         $cardinality = $options['cardinality'] ?? '';
         switch ($cardinality) {
             case 'to-one':
+                /** @var ToOneRelationship<T,P> $relationship */
                 $relationship = new ToOneRelationship($parent, $name, $options, $data);
                 break;
             case 'to-many':
+                /** @var ToManyRelationship<T,P> $relationship */
                 $relationship = new ToManyRelationship($parent, $name, $options, $data ?? []);
                 break;
             default: