Fixed some more inspection issues

src/Validator/Constraints/Misc/ValidRange.php

@@ -48,5 +48,5 @@ use Symfony\Component\Validator\Constraint;
  */
 class ValidRange extends Constraint
 {
-    public $message = 'validator.invalid_range';
+    public string $message = 'validator.invalid_range';
 }

src/Validator/Constraints/NoLockout.php

@@ -31,5 +31,5 @@ use Symfony\Component\Validator\Constraint;
  */
 class NoLockout extends Constraint
 {
-    public $message = 'validator.noLockout';
+    public string $message = 'validator.noLockout';
 }

src/Validator/Constraints/NoneOfItsChildren.php

@@ -35,9 +35,9 @@ class NoneOfItsChildren extends Constraint
     /**
      * @var string The message used if it is tried to assign a object as its own parent
      */
-    public $self_message = 'validator.noneofitschild.self';
+    public string $self_message = 'validator.noneofitschild.self';
     /**
      * @var string The message used if it is tried to use one of the children for as parent
      */
-    public $children_message = 'validator.noneofitschild.children';
+    public string $children_message = 'validator.noneofitschild.children';
 }

src/Validator/Constraints/UrlOrBuiltin.php

@@ -35,5 +35,5 @@ class UrlOrBuiltin extends Url
     /**
      * @var array A list of the placeholders that are treated as builtin
      */
-    public $allowed_placeholders = Attachment::BUILTIN_PLACEHOLDER;
+    public array $allowed_placeholders = Attachment::BUILTIN_PLACEHOLDER;
 }