Merge pull request numpy#27361 from eugo-inc/fix-ptrdiff_t-missing-include-in-cxx-23

BUILD: fix missing include for std::ptrdiff_t for C++23 language mode

Author: charris

numpy/_core/src/umath/string_fastsearch.h

@@ -9,6 +9,7 @@
 #include <wchar.h>
 
 #include <type_traits>
+#include <cstddef>
 
 #include <numpy/npy_common.h>