fix new device

selfprivacy_api/repositories/tokens/json_tokens_repository.py

@@ -210,7 +210,13 @@ class JsonTokensRepository(AbstractTokensRepository):
         self, mnemonic_phrase: str, device_name: str
     ) -> Token:
         """Use the mnemonic new device key"""
-        new_device_key = self.get_new_device_key()
+
+        with WriteUserData(UserDataFiles.TOKENS) as tokens_file:
+            new_device_key = NewDeviceKey(
+                key=tokens_file["new_device"]["token"],
+                created_at=tokens_file["new_device"]["date"],
+                expires_at=tokens_file["new_device"]["expiration"],
+            )
 
         if new_device_key is None:
             raise TokenNotFoundError("New device key not found!")