use C-string literal

Co-authored-by: Bennet Bleßmann <3877590+Skgland@users.noreply.github.com>

tests/scryer/ffi.rs

@@ -311,7 +311,7 @@ fn ffi_utf8_panic() {
         r##"
                 #[unsafe(no_mangle)]
                 extern "C" fn ffi_invalid_utf8_cstr() -> *const core::ffi::c_char {
-                    b"Invalid\xFFUTF8\x00".as_ptr() as *const _
+                    c"Invalid\xFFUTF8".as_ptr()
                 }
             "##,
     );