std.debug: remove `warn` (deprecated in 0.9)

Followup to 902df103c6151c257c90de9ba5f29f7f4b9dbea2.
Signed-off-by: Eric Joldasov <bratishkaerik@getgoogleoff.me>
f7dddd4c81Eric Joldasov committed on 6/13/2023, 5:46:58 PMparentee821b2
1 file changedLine totals unavailable