update rtdb regex

Author: tinaliang

delete-user-data/extension.yaml

@@ -106,8 +106,8 @@ params:
     label: Realtime Database paths
     example: users/{UID},admins/{UID}
     required: false
-    validationRegex: '^\S+$'
-    validationErrorMessage: Database path(s) cannot contain spaces.
+    validationRegex: '^[^\s.#$[\]]+$'
+    validationErrorMessage: Database path(s) contains spaces and/or invalid characters.
     description: >-
       Which paths in your Realtime Database instance contain user data? Leave empty if you
       don't use Realtime Database.