Fixed unit tests

src/myfasthtml/core/data/DataService.py

@@ -84,6 +84,9 @@ class DataService(MultipleInstance):
     self._store = DataStore(self, save_state=save_state)
     self._init_store()
   
+  def save_state(self):
+    self._state.save()
+  
   @property
   def columns(self) -> list[ColumnDefinition]:
     """Return the list of column definitions."""