Broken dependency + Unknown feature `stdsimd` + Is this still being worked on?
Hello!

Tried to compile Mithril, installed the nightly version of Rust like was asked.
When I tried to build Mithril, I got an error:
```
    Blocking waiting for file lock on package cache
    Updating git repository `https://github.com/Ragnaroek/rust-argon2`
error: failed to get `rust-argon2` as a dependency of package `mithril v0.20.0 (/home/usrr/mithril)`

Caused by:
  failed to load source for dependency `rust-argon2`

Caused by:
  Unable to update https://github.com/Ragnaroek/rust-argon2

Caused by:
  failed to fetch into: /home/usrr/.cargo/git/db/rust-argon2-4a0f8b07344c2b3f

Caused by:
  failed to authenticate when downloading repository

  * attempted to find username/password via git's `credential.helper` support, but failed

  if the git CLI succeeds then `net.git-fetch-with-cli` may help here
  https://doc.rust-lang.org/cargo/reference/config.html#netgit-fetch-with-cli

Caused by:
  failed to acquire username/password from local configuration
```

When I tried to reach the [Argon2](https://github.com/Ragnaroek/rust-argon) repository, I get a 404 page.
After getting the regular version of Argon2 from crates.io, and trying to compile again, I get another error:
```
error[E0635]: unknown feature `stdsimd`
  --> /home/usrr/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ahash-0.7.6/src/lib.rs:33:42
   |
33 | #![cfg_attr(feature = "stdsimd", feature(stdsimd))]
   |                                          ^^^^^^^

For more information about this error, try `rustc --explain E0635`.
error: could not compile `ahash` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
```

The last update was 3 years ago, will this project still be worked on, or should I look somewhere else?