Replace Dockerfile base with distroless

[sestrella]

Taking the Distroless Rust example as a reference, the existing Dockerfile could be split into different stages:

• One that compiles the project and generates a binary
• Another one that places that binary in a distroless image

The outcome would be a very tiny image. Taking into account that hapistrano is a deployment tool that is mostly executed by a CI pipeline, shrinking the image is beneficial since it would reduce the overhead produced by pulling the image from Docker Hub to the CI worker.