no rust-toolchain-aarch64-unknown-linux-gnu.tar.gz release version

[EricArcherman]

problematic when using aarch64 Linux computers wtih Jolt as the nightly toolchain download link generated by fn toolchain_url() (https://github.com/a16z/jolt/blob/137552a6c583f43a079e88898c2322ff5dc66a7e/jolt-core/src/host/toolchain.rs#L160) does not exist.

To fix: add a rust-toolchain-aarch64-unknown-linux-gnu.tar.gz to the releases listed here https://github.com/a16z/rust/releases/tag/nightly-8af9d45d5e09a04832cc9b2e1df993fd1ce49d02. I.e.:

• rust-toolchain-aarch64-apple-darwin.tar.gz
• rust-toolchain-x86_64-apple-darwin.tar.gz
• rust-toolchain-x86_64-unknown-linux-gnu.tar.gz
• more here like: rust-toolchain-aarch64-unknown-linux-gnu.tar.gz

[sagar-a16z]

Support for aarch64-unknown-linux-gnu was added here: #16