add linux-aarch64 built

[stschiff]

As requested on Bioconda here, we would like to add a linux-aarch64 built.

[stschiff]

Just an update for @dslarm, who requested this: I have managed to make Arm builds here on GitHub, but in the meantime the Docker-build for CentOS7 failed, so porting to bioconda is still not finished.

[dslarm]

Hi @stschiff - thanks for working on this and for the update - great progress!