upgrade alpine base image v3.12.2->v3.13.3 including upgrade of tor v0.4.4.7-r1->v0.4.4.8-r0 (see below)
> One of these vulnerabilities (TROVE-2021-001) would allow an attacker
> who can send directory data to a Tor instance to force that Tor
> instance to consume huge amounts of CPU.
https://gitweb.torproject.org/tor.git/plain/ChangeLog
https://cve.circl.lu/cve/CVE-2021-28089
https://git.alpinelinux.org/aports/commit/community/tor?id=dc7ce7e4b63c64d11026e307ada830c33d8309a4