Include support for darwin/arm64

[luklss]

You currently cannot install unicreds if you have a MAC with an M1 processor (arm64) without building from source (which for me was not really straighforward), unless you have Rosetta. Would be nice to have that build and released by default as well.

[luklss]

Just to add to that, if you have a darwvin arm64 system (even with Rosetta), brew won't install unicreds. The error is the following:

unicreds: The x86_64 architecture is required for this software.
Error: unicreds: An unsatisfied requirement failed this build.