package/stunnel: bump to version 5.58
Update COPYING hash; copyright year update:
-_Copyright (C) 1998-2020 Michal Trojnara_
+_Copyright (C) 1998-2021 Michal Trojnara_
See full changelog https://www.stunnel.org/NEWS.html
Signed-off-by: Pierre-Jean Texier <texier.pj2@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>