v3.20.3

With this version, the Alpine image will be always fixed in the Dockerfile, for an easier and robust control.
As the original software is not getting updates (it works flawlessly, nonetheless), this Docker image will follow the versions of Alpine for the versioning.

New

• Bump Alpine version to 3.20.3 from 3.19.1 c6dd8a2
• Fix Alpine version in Dockerfile c6dd8a2