Update user_providers.rst

Adding return type to serveral functions

Author: hbgamra

security/user_providers.rst

@@ -314,7 +314,7 @@ command will generate a nice skeleton to get you started::
          *
          * @return UserInterface
          */
-        public function refreshUser(UserInterface $user)
+        public function refreshUser(UserInterface $user): UserInterface
         {
             if (!$user instanceof User) {
                 throw new UnsupportedUserException(sprintf('Invalid user class "%s".', get_class($user)));
@@ -328,7 +328,7 @@ command will generate a nice skeleton to get you started::
         /**
          * Tells Symfony to use this provider for this User class.
          */
-        public function supportsClass(string $class)
+        public function supportsClass(string $class): bool
         {
             return User::class === $class || is_subclass_of($class, User::class);
         }