upgrade alpine base image v3.13.2->3.13.3 including openssh-server package upgrade v8.4_p1-r2->v8.4_p1-r3 (diff links below, CVE-2020-14145 only relevant for clients)
https://ubuntu.com/security/CVE-2020-14145
https://git.alpinelinux.org/aports/commit/main/openssh?id=3a797aaebe72b0c92b602223a960d273986cbc46
https://git.alpinelinux.org/aports/commit/main/openssh?id=c73bf359dd445e718165b219c14a4bd3779cede2
https://github.com/fphammerle/docker-ssh-bastion/commit/a36338c425756d78273a86ffe17985a5d90f2d39