support manifest v3

Hello, do you plan to develop a version for the third version manifest?

It is already available, and I would like to use it in production.
> January 17, 2022: New Manifest V2 extensions will no longer be accepted by the Chrome Web Store. Developers may still push updates to existing Manifest V2 extensions, but no new Manifest V2 items may be submitted.

[source](https://developer.chrome.com/blog/mv2-transition/)

The issue names no files, tests, or entry point. Start by locating how this JavaScript WebExtension defines or consumes its manifest, then consult the linked Chrome Manifest V2 transition guidance; the issue does not specify acceptance criteria for Manifest V3 support.

Written by the indexing model from the issue text.