Use official Docker GitHub actions
Use official Docker GitHub actions

Use the following actions instead of manual setup:
- https://github.com/docker/login-action
- https://github.com/docker/setup-qemu-action
- https://github.com/docker/build-push-action
- https://github.com/peter-evans/dockerhub-description

Notes:
- It would be good to merge "Build and push" and "Build and push
  (alpine)" steps but I have no solution to propose for now;
- I am using token and 2FA on DockerHub so the update description step
  could not be tested.

mvdan/sh,mvdan/sh,mvdan/sh,mvdan/sh