make use of setsid(1)'s -f flag (#652)

Co-authored-by: Luke Smith <luke@lukesmith.xyz>

.local/bin/compiler

@@ -35,6 +35,6 @@ case "$file" in
 	*\.m) octave "$file" ;;
 	*\.scad) openscad -o "$base".stl "$file" ;;
 	*\.go) go run "$file" ;;
-	*\.sent) setsid sent "$file" 2>/dev/null & ;;
+	*\.sent) setsid -f sent "$file" 2>/dev/null ;;
 	*) sed 1q "$file" | grep "^#!/" | sed "s/^#!//" | xargs -r -I % "$file" ;;
 esac