fix quotes in quotes typo

Signed-off-by: David Wallace <david.wallace@tu-darmstadt.de>

Author: MyPyDavid

rdmo_client/client/rest.py

@@ -9,7 +9,7 @@ def _build_url(self, resource_url, kwargs, pk=None):
         if 'list_route' in kwargs:
             url += kwargs.pop('list_route').rstrip('/') + '/'
         elif 'nested_route' in kwargs:
-            url += f'{kwargs.pop('parent_pk')}/'
+            url += f'{kwargs.pop("parent_pk")}/'
             url += kwargs.pop('nested_route').rstrip('/') + '/'
 
         if pk: