fix: update Dockerfile and fix clippy

[rapiz1]

rust-musl-builder is mostly unmaintained and cargo broke things.

So our Dockerfile failed to build, as reported in #200 (comment)

This PR adopts the Dockerfile based on the official rust image rust:alpine. It builds musl by default because alpine is based on musl. It also turns off the tls feature explicitly. It never works in the docker image since missing the dynlib. Disabling the feature should give users a clear error message when trying tls.

FYI @orhun

[orhun]

Good stuff! I was aware of the issue and it is good to see an alternative MUSL build approach. Thanks for the ping!