internal/rosa: use builtin for checksum warning

This avoids having to configure the logger early.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -3,7 +3,6 @@ package rosa
 
 import (
 	"errors"
-	"log"
 	"path"
 	"runtime"
 	"slices"
@@ -28,7 +27,7 @@ const (
 func mustDecode(s string) pkg.Checksum {
 	var fallback = pkg.Checksum{}
 	if s == "" {
-		log.Println(
+		println(
 			"falling back to",
 			pkg.Encode(fallback),
 			"for unpopulated checksum",