Streamline releases!

[imikushin]

Feature Request

Make releasing a new version of Dispatch as easy as:

1. Submit a PR for the release (as usual).
2. Add release label to the PR (you should also add run-e2e, it can be added automatically though).
3. Wait for the PR to get approved!

Detailed Description

Once the PR is approved and it has the release label (and run-e2e, and all the checks have passed), the release pipeline kicks off. The release pipeline does the following:

1. locally git-tag the latest commit of the PR with the version tag (e.g. v0.1.22)
2. build the release artifacts off the tagged commit
3. merge the PR (with a merge commit, NOT squash-merge or rebase)
4. push the version tag to GitHub (git push --tags)
5. create the release off the version tag on GitHub and upload the release artifacts

Context

As part of the Dispatch release process you already have to submit a "release" PR with updates to CHANGELOG and the release notes. This proposal seeks to automate the manual steps.

Complexity

• [ ] Low - Simple enhancement or bug fix, no architectural changes or refactoring
• [x] Medium - Change requires some thought, but is relatively isolated
• [ ] High - Significant architectural change or large refactor