schelling_experimental: Remove temporary _advance_time() method (#162)

Remove the remove temporary _advance_time() method from schelling_experimental. This isn't needed anymore, because in Mesa 3.0 time will be automatically increased.

Author: EwoutH

examples/schelling_experimental/model.py

@@ -66,8 +66,6 @@ def step(self):
         """
         self.happy = 0  # Reset counter of happy agents
         self.agents.shuffle().do("step")
-        # Must be before data collection.
-        self._advance_time()  # Temporary API; will be finalized by Mesa 3.0 release
         # collect data
         self.datacollector.collect(self)