Long-term support (LTS) release for JupyterLab

[JasonWeill]

Problem

JupyterLab doesn't have a long-term support release, a major or minor version that the team commits to have supported beyond the normal maintenance timeline (see #231). Large users of JupyterLab, like corporations and educational institutions, find it difficult and expensive to upgrade often.

Proposed Solution

Designate one or more major/minor versions of JupyterLab as long-term support (LTS) releases, which we commit to maintain with critical feature updates for longer than non-LTS releases. Non-LTS release users will get more features sooner, but they are also responsible for upgrading more often to continue to receive maintenance updates.

We discussed this off the record at the 2024-02-14 JupyterLab weekly call.

Additional context

Firefox has an LTS release, called ESR (extended support release) documented here: https://www.mozilla.org/en-US/firefox/enterprise/

NodeJS uses an LTS schedule for even-numbered releases only, documented here: https://nodejs.org/en/about/previous-releases