[BUGFIX] Restore PHP 8.1 support

Fixes: #654

Classes/Definition/TcaFieldDefinition.php

@@ -27,30 +27,30 @@
 final class TcaFieldDefinition
 {
     private const ALLOWED_EMPTY_VALUES_BY_TYPE = [
-        FieldType::SELECT->value => [
+        'select' => [
             'config.items',
         ],
-        FieldType::CHECK->value => [
+        'check' => [
             'config.items',
         ],
         // This is important for upgrades, to keep something in the "config" array.
         // In TYPO3 v12 type="inline" with foreign_table="sys_file_reference" is now type="file".
         // Because of this, Mask does not have any standard TCA for this field anymore.
         // The removeBlankOptions method would thus remove everything and the next save in the backend builder would
         // result in the file field to be treated as a "coreField".
-        FieldType::FILE->value => [
+        'file' => [
             'config.minitems',
         ],
-        FieldType::MEDIA->value => [
+        'media' => [
             'config.minitems',
         ],
     ];
 
     private const STOP_RECURSIVE_VALUES_BY_TYPE = [
-        FieldType::SELECT->value => [
+        'select' => [
             'config.itemGroups',
         ],
-        FieldType::SLUG->value => [
+        'slug' => [
             'config.generatorOptions.replacements',
         ],
     ];