Add missing extension

composer.json

@@ -23,6 +23,7 @@
     "symfony/options-resolver": "^4.2",
     "symfony/property-access": "^4.3",
     "symfony/serializer": "^4.2",
+    "tritum/form-element-linked-checkbox": "^2.1",
     "typo3/cms-adminpanel": "^10.4",
     "typo3/cms-backend": "^10.4",
     "typo3/cms-belog": "^10.4",