NPM packages are published through CI/CD in the .github/workflows/master.yml workflow. Every commit that is merged to master will be checked for new versions of all public packages, and any new versions will automatically be published to NPM.
Version bumps are made through release PRs. To create a new release, checkout out a new branch that you will use for the release, e.g.
$ git checkout -b new-release
Then, from the root of the repo, run
$ yarn release
This will bring up the lerna release CLI where you choose what type of version bump you want to make, (major/minor/patch/prerelease). The CLI will take you through choosing a version, previewing all changes, and then approving the release. Once the release is approved, a new commit is created that you can submit as a PR. Push the branch to GitHub:
$ git push origin -u new-release
And then create a PR. Once the PR is approved and merged into master, the master build will publish new versions of all bumped packages.