Fix minor typo in qmk_install.sh for MSYS/MINGW64 detection

util/qmk_install.sh

@@ -10,7 +10,7 @@ case $(uname) in
 	Linux)
 		exec "${util_dir}/linux_install.sh"
 	;;
-	MSYS_NT*|MINGW_64*)
+	MSYS_NT*|MINGW64_NT*)
 		exec "${util_dir}/msys2_install.sh"
 	;;
 esac