BUG: don't duplicate norm parameter for scatter plots (pandas-dev#45809)

Author: Andy-Grigg

pandas/plotting/_matplotlib/core.py

@@ -1105,7 +1105,7 @@ def _make_plot(self):
             bounds = np.linspace(0, n_cats, n_cats + 1)
             norm = colors.BoundaryNorm(bounds, cmap.N)
         else:
-            norm = None
+            norm = self.kwds.pop("norm", None)
         # plot colorbar if
         # 1. colormap is assigned, and
         # 2.`c` is a column containing only numeric values