windows: pass rune to %q formatting verb

It's caught by Go 1.26's vet check that the format %q here
is given a wrong type uint16. Convert it to a rune instead.

Change-Id: Ic6eb4d0c64c898f008ca47e694ac2f45d2cd9965
Reviewed-on: https://go-review.googlesource.com/c/sys/+/818181
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ayman Bagabas <ayman.bagabas@gmail.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

windows/syscall_windows_test.go

diff --git a/windows/syscall_windows_test.go b/windows/syscall_windows_test.go
index 92da6bd..ef05fdc 100644
--- a/windows/syscall_windows_test.go
+++ b/windows/syscall_windows_test.go
@@ -1473,7 +1473,7 @@
 		t.Errorf("ToUnicodeEx failed, wanted 1, got %d", ret)
 	}
 	if utf16Buf[0] != 'ش' {
-		t.Errorf("ToUnicodeEx failed, wanted 'ش', got %q", utf16Buf[0])
+		t.Errorf("ToUnicodeEx failed, wanted 'ش', got %q", rune(utf16Buf[0]))
 	}
 	if err := windows.UnloadKeyboardLayout(araLayout); err != nil {
 		t.Errorf("UnloadKeyboardLayout failed: %v", err)