Support `arm64` binary

[bentsherman]

This issue came up in a conversation with Paolo. The migtool release should include an arm64 binary for linux / macOS, so that it can run natively on machines like Paolo's laptop. 😄 We will use a workaround for now, so it's not urgent, but it would be good to have in the long term.

[munishchouhan]

@bentsherman I am facing connectivity issue in mac with mysql
can you please share the workaround?

[bentsherman]

Our workaround was to create a simple Java project that calls the migtool library:

https://github.com/seqeralabs/groundswell/tree/master/migtool

But based on our discussion it sounds like migtool isn't the issue but your connection with mysql.

[bentsherman]

The latest release of Tower CLI includes a native build for arm64, let's add this to migtool