Resolve "Deploy git tag containers"

What does this MR do?

Adds GitLab CI rules to deploy git tags and a branch called latest. Deploys will be hosted on the GitLab registry and the debian_gcc pipeline will be regarded labelled as the latest from the latest branch. Thus, latest branch must be the commit to the latest stable release.

Can this MR be accepted?

• Implemented
• Pipelines passing
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  • 
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• Delete branch option set
• Added entry to CHANGELOG.md

Related issues

Closes #35 (closed)