Adjust DynamicReturnTypeInterface::getClass to non static method

Make compatible with latest phpstan master by changing the getClass
method of the DynamicReturnTypeInterface to a non static method

Author: sascha-egerer

src/Type/GeneralUtilityDynamicReturnTypeExtension.php

@@ -12,7 +12,7 @@
 
 class GeneralUtilityDynamicReturnTypeExtension implements DynamicStaticMethodReturnTypeExtension
 {
-    public static function getClass(): string
+    public function getClass(): string
     {
         return \TYPO3\CMS\Core\Utility\GeneralUtility::class;
     }

src/Type/ObjectManagerDynamicReturnTypeExtension.php

@@ -12,7 +12,7 @@
 
 class ObjectManagerDynamicReturnTypeExtension implements DynamicMethodReturnTypeExtension
 {
-    public static function getClass(): string
+    public function getClass(): string
     {
         return \TYPO3\CMS\Extbase\Object\ObjectManagerInterface::class;
     }

src/Type/QueryInterfaceDynamicReturnTypeExtension.php

@@ -17,7 +17,7 @@
 
 class QueryInterfaceDynamicReturnTypeExtension implements DynamicMethodReturnTypeExtension
 {
-    public static function getClass(): string
+    public function getClass(): string
     {
         return QueryInterface::class;
     }