Fix for Dockerfile smell DL3007

[grosa1]

Hi!
The Dockerfile placed at "Dockerfile" contains the best practice violation DL3007 detected by the hadolint tool.

The smell DL3007 occurs when the tag "latest" is used instead of a specific version tag for the base image.
In this pull request, we propose a fix for that smell generated by our fixing tool. We have verified that the patch is correct before opening the pull request.
To fix this smell, specifically, we use a heuristic approach that selects the most probable version tag for the base image in order to replace the "latest" tag. In detail, it selects the most recent image tag which corresponds to the same image digest that currently corresponds to the "latest" tag.

This change is only aimed at fixing that specific smell. If the fix is not valid or useful, please briefly indicate the reason and suggestions for possible improvements.

Thanks in advance

[chandanpasunoori]

I appreciate the detailed pull request, happy to merge but I still feel not justified, as this only affects at build time and automatically tested in ci test

also by running in latest alpine version, its always guaranteed to be up to date with current changes/patches of os and security updates new vulnerabilities

[grosa1]

Hi @chandanpasunoori,
the patch is only for the reliability of the image in case of an update that could lead to failures in the current content of the Dockerfile.
The version tag could be less restrictive like FROM alpine3 to catch all the updates and fix the major version. Maybe it will be better in that case