Automatically bump version when merging pull requests

[loket]

It would be very useful if the version package.json file could be updated automatically, on every pull request. It will need some sort of "classifier", to know whether to bump major, minor or patch version.

Here's an Action that can be used: https://github.com/marketplace/actions/automated-version-bump

[loket]

I just got a tip about this repo: https://github.com/googleapis/release-please

Looks way better!