Setup fails in Linux ARM64 platforms

[adpaco]

cargo kani setup fails to download the bundle for the aarch64-unknown-linux-gnu platform.

[0/5] Running Kani first-time setup...
[1/5] Ensuring the existence of: /home/accorell/.kani/kani-0.40.0
[2/5] Downloading Kani release bundle: kani-0.40.0-aarch64-unknown-linux-gnu.tar.gz
Error: Kani does not support this platform (Rust target aarch64-unknown-linux-gnu)

with Kani version: 0.40.0

The problem is that the setup program contains a platform check that which hasn't been updated.

[adpaco]

It's possible to work around this failure by manually executing the remaining cargo kani setup steps:

1. Download the kani-0.40.0-aarch64-unknown-linux-gnu.tar.gz bundle.
2. Unpack the bundle: tar -zxf kani-0.40.0-aarch64-unknown-linux-gnu.tar.gz (this will generate a kani-0.40.0 folder)
3. Copy the bundle: cp -r kani-0.40.0 ~/.kani/
4. Install the nightly toolchain: rustup toolchain install nightly-2023-10-31
5. Link the toolchain: ln -s ~/.rustup/toolchains/nightly-2023-10-31-aarch64-unknown-linux-gnu ~/.kani/kani-0.40.0/toolchain
6. (optional) Install Python dependencies: python3 -m pip install --target ~/.kani/kani-0.40.0/pyroot cbmc-viewer==3.8