feat: Generate :next and :edge docker tags

[Falx]

📁 Related issues

#1140

✍️ Description

This PR will add 2 new docker tags to the official docker image by updating the CI.

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branch: main
docker tag: :edge

This tag would be generated on each commit push on the main branch. The idea is that you can have a docker image of the latest developments. I suggest :edge in favor of the earlier proposed :dev tagname, because it better self-explains what it is. It is on the edge of the main repository. If you need that for development, you'll pick it.
If we were to use the :dev tag, you first have to at least find out what that really means.

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branch: versions/*
docker tag: :next

This tag would be generated on each commit push on the versions/* branch. There should only be one version there that is being prepared. This tag will guarantee an image with the latest upcoming version features.

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✅ PR check list

Before this pull request can be merged, a core maintainer will check whether

• this PR is labeled with the correct semver label
  • semver.patch: Backwards compatible bug fixes.
  • semver.minor: Backwards compatible feature additions.
  • semver.major: Breaking changes. This includes changing interfaces or configuration behaviour.
• the correct branch is targeted. Patch updates can target main, other changes should target the latest versions/* branch.
• the RELEASE_NOTES.md document in case of relevant feature or config changes.

[joachimvh]

Looks good, thanks!