Run E2E tests against the latest stable version of Gutenberg

### Is your feature request related to a problem? Please describe.

Yes. Changes in Gutenberg can break CoBlocks and vice-versa. Here's a recent example of a bug that happens when a recent version of CoBlocks is activated alongside a relatively recent version of Gutenberg: https://github.com/godaddy-wordpress/coblocks/issues/2474.

Since CoBlocks extends and depends on Gutenberg, changes in Gutenberg can affect CoBlocks, and changes in CoBlocks could also affect Gutenberg.

### Describe the solution you'd like

**Add a new job to test against the **latest stable** version of Gutenberg in PRs and/or recurringly. I'm thinking about the E2E tests here.**

I'm not too acquainted with the CoBlocks source, but I assume that E2Es are running against the built-in block editor that comes with WPorg, which is usually equivalent to a pretty old version of Gutenberg.

Thanks!