Building DFX on aarch64-linux

[chmllr]

Dear SDK team, is there a good reason for restricting the supported builds for linux and windows to x86_64 only?

https://github.com/dfinity/sdk/blob/master/src/dfx/assets/build.rs#L102

I'm trying to build in a Ubuntu VM hosted on macOS and get the panic on line 103 of the linked file because the OS cannot be recognized. But simply changing the line 102 to this, produces a working build:

("x86_64" | "aarch64", "linux" | "windows") => sources.x86_64_linux,

Please consider relaxing the architecture matching 🙏