The following packages have unmet dependencies:
zcash : Depends: libc6 (>= 2.28) but 2.24-11+deb9u4 is to be installed
E: Unable to correct problems, you have held broken packages.
I have tried to install libc6 but it does not solve this issue. Some idea how to fix it?
You will likely want to update that stretch resource in the linked dockerfile to buster or bullseye. We no longer support Stretch due to upcoming EOS and focus on other platforms.