Update circle ci for mac os arm64

[rehlma]

I have updated the CircleCI config to make it work with M1 (arm64).

The problem was the wrong dart-sdk for arm64.

As you can see here, I tested it with CircleCI and MacOS is working again.

[passsy]

@pingbird Can we get a new release?

[pingbird]

We need to continue supporting x86 macs so this alone would not work

[pingbird]

I have fixed the build issue w/ Rosetta, but if you want to add a separate build step for arm64 binaries and fix any relevant os detecting code (e.g. the install script) i will likely merge it