stages/prompt: force required to false when using readonlyfield

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/stages/prompt/models.py

@@ -148,6 +148,8 @@ class Prompt(SerializerModel):
             kwargs["allow_blank"] = not self.required
         if self.type == FieldTypes.TEXT_READ_ONLY:
             field_class = ReadOnlyField
+            # required can't be set for ReadOnlyField
+            kwargs["required"] = False
         if self.type == FieldTypes.EMAIL:
             field_class = EmailField
             kwargs["allow_blank"] = not self.required