remove unused "type: ignore" comments in test_plot.py (fixed in matpl…

…otlib 3.10.0) (#9904)

xarray/tests/test_plot.py

@@ -90,27 +90,27 @@ def text_in_fig() -> set[str]:
     """
     Return the set of all text in the figure
     """
-    return {t.get_text() for t in plt.gcf().findobj(mpl.text.Text)}  # type: ignore[attr-defined] # mpl error?
+    return {t.get_text() for t in plt.gcf().findobj(mpl.text.Text)}
 
 
 def find_possible_colorbars() -> list[mpl.collections.QuadMesh]:
     # nb. this function also matches meshes from pcolormesh
-    return plt.gcf().findobj(mpl.collections.QuadMesh)  # type: ignore[return-value] # mpl error?
+    return plt.gcf().findobj(mpl.collections.QuadMesh)
 
 
 def substring_in_axes(substring: str, ax: mpl.axes.Axes) -> bool:
     """
     Return True if a substring is found anywhere in an axes
     """
-    alltxt: set[str] = {t.get_text() for t in ax.findobj(mpl.text.Text)}  # type: ignore[attr-defined] # mpl error?
+    alltxt: set[str] = {t.get_text() for t in ax.findobj(mpl.text.Text)}
     return any(substring in txt for txt in alltxt)
 
 
 def substring_not_in_axes(substring: str, ax: mpl.axes.Axes) -> bool:
     """
     Return True if a substring is not found anywhere in an axes
     """
-    alltxt: set[str] = {t.get_text() for t in ax.findobj(mpl.text.Text)}  # type: ignore[attr-defined] # mpl error?
+    alltxt: set[str] = {t.get_text() for t in ax.findobj(mpl.text.Text)}
     check = [(substring not in txt) for txt in alltxt]
     return all(check)
 
@@ -122,7 +122,7 @@ def property_in_axes_text(
     Return True if the specified text in an axes
     has the property assigned to property_str
     """
-    alltxt: list[mpl.text.Text] = ax.findobj(mpl.text.Text)  # type: ignore[assignment]
+    alltxt: list[mpl.text.Text] = ax.findobj(mpl.text.Text)
     return all(
         plt.getp(t, property) == property_str
         for t in alltxt