Update dependencies.

See merge request !36

Redox unix

See merge request !35

fix return statement of else block in dup function

See merge request !34

Update Cargo.lock

See merge request !32

A 'precise' cargo update of tokio is needed for the build to succeed.

cargo update

See merge request !31

Fixed packet buffer logic error in smoltcp

Update smoltcp

Closes #30

See merge request !30