chore: style fixes from go fix (#10846)

Just `go fix ./...`

Signed-off-by: Jakob Borg <jakob@kastelo.net>

lib/syncthing/superuser_unix.go

@@ -5,7 +5,6 @@
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
 //go:build !windows
-// +build !windows
 
 package syncthing
 

lib/syncthing/syncthing.go

@@ -458,7 +458,7 @@ func printServiceTree(w io.Writer, sup supervisor, level int) {
 	}
 }
 
-func printService(w io.Writer, svc interface{}, level int) {
+func printService(w io.Writer, svc any, level int) {
 	type errorer interface{ Error() error }
 
 	t := "-"