Automated version bump when new releases are out

[jtpio]

Problem

For now we manually update this repo to bump the version of jupyterlite when there is a new release. For example: #43

It would be great if this could be automated instead.

Proposed Solution

Probably just parsing and writing to requirements.txt should be enough for now.

Additional context

JupyterLab Desktop has a workflow to do that with JupyterLab releases: https://github.com/jupyterlab/jupyterlab-desktop/blob/master/.github/workflows/sync_lab_release.yml

[jtpio]

Or maybe there is a way to use the dependabot.yml workflow directly: https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file