update return type of Axes.axhspan and Axes.axvspan in interface

Author: chrille0313

lib/matplotlib/axes/_axes.pyi

@@ -155,10 +155,10 @@ class Axes(_AxesBase):
     ) -> AxLine: ...
     def axhspan(
         self, ymin: float, ymax: float, xmin: float = ..., xmax: float = ..., **kwargs
-    ) -> Polygon: ...
+    ) -> Rectangle: ...
     def axvspan(
         self, xmin: float, xmax: float, ymin: float = ..., ymax: float = ..., **kwargs
-    ) -> Polygon: ...
+    ) -> Rectangle: ...
     def hlines(
         self,
         y: float | ArrayLike,

lib/matplotlib/pyplot.py

@@ -2882,7 +2882,7 @@ def axhline(y: float = 0, xmin: float = 0, xmax: float = 1, **kwargs) -> Line2D:
 @_copy_docstring_and_deprecators(Axes.axhspan)
 def axhspan(
     ymin: float, ymax: float, xmin: float = 0, xmax: float = 1, **kwargs
-) -> Polygon:
+) -> Rectangle:
     return gca().axhspan(ymin, ymax, xmin=xmin, xmax=xmax, **kwargs)
 
 
@@ -2920,7 +2920,7 @@ def axvline(x: float = 0, ymin: float = 0, ymax: float = 1, **kwargs) -> Line2D:
 @_copy_docstring_and_deprecators(Axes.axvspan)
 def axvspan(
     xmin: float, xmax: float, ymin: float = 0, ymax: float = 1, **kwargs
-) -> Polygon:
+) -> Rectangle:
     return gca().axvspan(xmin, xmax, ymin=ymin, ymax=ymax, **kwargs)