Add a workflow to push the container image to GitHub's container registry

[danvergara]

Description

This PR add workflow to push the container image to GitHub's container registry.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Published the image omitting the branch constraint, for testing purposes.

Image is available by running:

docker pull ghcr.io/danvergara/morphos-server:latest

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings