ARM builds are useful for those wanting to generate keys on an offline ARM machine, most accessible of which is a raspberry pi. Currently, to use eth2.0-deposit-cli on an ARM machine, the user must connect to the internet to install dependencies. This defeats the purpose of an offline machine. This PR would close #82 .

The first commit creates build-linux-arm, a copy of build-linux which uses an ARM CI environment, freely supported by Circle CI. However, the current specified version of PyInstaller (3.6) required for building the binary fails to compile due to warnings and -Werror: Circle CI link for the first commit.

The second commit updates PyInstaller to the latest version (4.7). Just doing this also fails, as transitive dependencies of PyInstaller are not pinned to a specific version, which is required by the hashes. Just as in the project's root requirements.txt, the specific versions of transitive dependencies are specified at the bottom of build_configs/linux/requirements.txt. Since these dependencies were only specified with >=, I opted to use the latest versions of the underspecified packages (links provided for convenient checking of the hashes):

• pyinstaller-hooks-contrib 2021.4
• importlib-metadata 4.9.0
• typing-extensions 4.0.1
• zipp 3.6.0

The build-linux CI job continues to pass with the updated dependencies: Circle CI link for build-linux and build-linux-arm. I tested the ARM artifacts produced on an emulated qemu ARM vm and it seems to work fine. I will test on a raspberry pi later today