Fix handling for non-v0 tags

[xmudrii]

The publishing-bot repos have two remotes: origin (pointing to the real repo) and upstream (pointing to the clone of kcp-dev/kcp). Hence, the previously implemented tags handling logic didn't work at all. Additionally, Go pseudo-version strings are a bit more complicated than originally anticipated. We are now handling the following scenarios:

• the latest commit has a tag -> return tag as module version
• the repo does not have tags at all -> return v0.0.0-<commit-timestamp>-<commit-hash>
• the latest tag in the repo is a prerelease tag -> return <tag>.0.<commit-timestamp>-<commit-hash>
• the latest tag in the repo is a stable version tag -> return v<major>.<minor>.<patch+1>-0.<commit-timestamp>-<commit-hash>
• the latest tag's major version does not match the module's major version -> return <tag>+incompatible

/assign @xrstf

[xrstf]

/approve
/lgtm

[kcp-ci-bot]

LGTM label has been added.

Git tree hash: a29965c03aa6e432e88717fff21c43ece3ec2125

[kcp-ci-bot]

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