Stop using sprintf in builtin_random

fish-rust/src/builtins/random.rs

@@ -162,6 +162,6 @@ fn parse_ull(streams: &mut io_streams_t, cmd: &wstr, num: &wstr) -> Result<u64,
     // Safe because end was a valid i64 and the result here is in the range start..=end.
     let result: i64 = start.checked_add_unsigned(rand * step).unwrap();
 
-    streams.out.append(sprintf!(L!("%lld\n"), result));
+    streams.out.appendln(result.to_wstring());
     return STATUS_CMD_OK;
 }