add AARCH64 support on Linux

[stlankes]

RustyHermit is partly running on aarch64. We should support it also for uhyve.

[n0toose]

During some testing for #641 and #701, I tried the following on 6.1.0-rpi8-rpi-v8 (2024-01-25, aarch64) on my personal Raspberry Pi 5:

$ cargo install --locked uhyve
Updating crates.io 
Downloaded uhyve v0.3.
Downloaded 1 crate (63.7 KB) in 1.
Installing uhyve v0.3.
error: failed to select a version for `env_logger`.
... required by package `uhyve v0.3.0`
versions that meet the requirements `^0.11` (locked to 0.11.3) are: 0.11.3
         
the package `uhyve` depends on `env_logger`, with features: `anstream` but `env_logger` does not have these features.

It has an optional dependency with that name, but that dependency uses the "dep:" syntax in the features table, so it does not have an implicit feature with that name.
                  
failed to select a version for `env_logger` which could resolve this conflict

Looks like that's the first blocker for the time being.