chore: bump ooniprobe version to 3.27.0-alpha (ooni#1715)

## Checklist

- [ ] I have read the [contribution
guidelines](https://github.com/ooni/probe-cli/blob/master/CONTRIBUTING.md)
- [ ] reference issue for this pull request: <!-- add URL here -->
- [ ] if you changed anything related to how experiments work and you
need to reflect these changes in the ooni/spec repository, please link
to the related ooni/spec pull request: <!-- add URL here -->
- [ ] if you changed code inside an experiment, make sure you bump its
version number

<!-- Reminder: Location of the issue tracker:
https://github.com/ooni/probe -->

## Description

We are now hacking on 3.27.0-alpha