Merge pull request matplotlib#28564 from meeseeksmachine/auto-backport-of-pr-28534-on-v3.9.x

Backport PR matplotlib#28534 on branch v3.9.x ([BLD] Fix WSL build warning)

Author: QuLogic

src/_image_resample.h

@@ -500,7 +500,7 @@ typedef enum {
 
 // T is rgba if and only if it has an T::r field.
 template<typename T, typename = void> struct is_grayscale : std::true_type {};
-template<typename T> struct is_grayscale<T, decltype(T::r, void())> : std::false_type {};
+template<typename T> struct is_grayscale<T, std::void_t<decltype(T::r)>> : std::false_type {};
 
 
 template<typename color_type>