[Security] Add missing void PHPdoc return types

Author: mbuliard

Tests/Fixtures/User.php

@@ -54,7 +54,7 @@ public function getUserIdentifier(): string
         return $this->name;
     }
 
-    public function eraseCredentials()
+    public function eraseCredentials(): void
     {
     }
 

Tests/Form/ChoiceList/ORMQueryBuilderLoaderTest.php

@@ -280,17 +280,11 @@ public function __construct()
     {
     }
 
-    /**
-     * @return array|string
-     */
-    public function getSQL()
+    public function getSQL(): array|string
     {
     }
 
-    /**
-     * @return Result|int
-     */
-    protected function _doExecute()
+    protected function _doExecute(): Result|int
     {
     }
 }