docker: bring back alpine 3.12
Created by: stefanhengl
While the upgrade to alpine 3.14 is ongoing, we still want to bump the alpine-3.12 to a new patch release.
This reintroduces the alpine-3.12 docker image which I prematurely removed in #28126.
Created by: stefanhengl
While the upgrade to alpine 3.14 is ongoing, we still want to bump the alpine-3.12 to a new patch release.
This reintroduces the alpine-3.12 docker image which I prematurely removed in #28126.