Add aarch64 as a known alternative to arm64

[Dr-Emann]

aarch64 is the official name for the 64-bit ARM architecture.

For example, https://github.com/obi1kenobi/cargo-semver-checks/releases/tag/v0.31.0 has releases with names:

• cargo-semver-checks-aarch64-apple-darwin.tar.gz
• cargo-semver-checks-aarch64-unknown-linux-gnu.tar.gz
• cargo-semver-checks-aarch64-unknown-linux-musl.tar.gz

which are currently not found by this action on e.g. an arm64 apple github runner.

[Dr-Emann]

related to #65, #61

[jaxxstorm]

Thanks for the contribution!