Remove refresh function from polar ThetaLocator

The Locator `refresh` method was deprecated in 3.3 and removed in 3.5.
But this subclass was apparently missed in the removal process.

As such, this method will raise if called, thus I do not personally
think it requires a separate deprecation period or even api note (though
willing to do so if others disagree, of course)

Author: ksunden

lib/matplotlib/projections/polar.py

@@ -253,10 +253,6 @@ def __call__(self):
         else:
             return np.deg2rad(self.base())
 
-    def refresh(self):
-        # docstring inherited
-        return self.base.refresh()
-
     def view_limits(self, vmin, vmax):
         vmin, vmax = np.rad2deg((vmin, vmax))
         return np.deg2rad(self.base.view_limits(vmin, vmax))