Several updates

[eldruin]

• Raised MSRV to 1.46.0 due to nix
• Updated nix
• Renamed use_tokio feature async-tokio like in gpio-cdev. (The word "use" is discouraged in feature names: C-FEATURE)
• Fixed docs link
• Use GHA for CI instead of Travis (tested on my fork)
• Added embedded-linux team to authors

Fixes #66

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @ryankurte (or someone else) soon.

Please see the contribution instructions for more information.

[eldruin]

bors try

[posborne]

Updates LGTM. I think one additional thing we could add that was requested elsewhere would be the specify features as part of package.metadata.docs.rs in order to include the tokio docs in what gets published to docs.rs.

[eldruin]

Sounds good. I will add that in a separate PR, thanks!

[bors]

try

Timed out.