Editor: Bump pinned hash for the Gutenberg repository.

This updates the pinned hash from the `gutenberg` from `7b7fa2bc97a8029a302bd6511cf0d206b5953172` to `9b8144036fa5faf75de43d4502ff9809fcf689ad`.

The following changes are included:

- Use V2 Yjs methods for HTTP Polling (https://github.com/WordPress/gutenberg/pull/76304)
- Plugin: Include Icons assets in ZIP (https://github.com/WordPress/gutenberg/pull/75866)
- Ensure consistent, repeatable build results when inlining WASM files via `wasmInlinePlugin`  (https://github.com/WordPress/gutenberg/pull/76113)
- Account `IS_WORDPRESS_CORE` is set. (https://github.com/WordPress/gutenberg/pull/76334)
- Block Visibility: Add `fetchpriority=auto` to `IMG` tags in blocks with conditional viewport visibility to prevent potential erroneous high loading priority (https://github.com/WordPress/gutenberg/pull/76302)

A full list of changes can be found on GitHub: https://github.com/WordPress/gutenberg/compare/7b7fa2bc97a8029a302bd6511cf0d206b5953172…9b8144036fa5faf75de43d4502ff9809fcf689ad.

See #64595, #64393.

git-svn-id: https://develop.svn.wordpress.org/trunk@61870 602fd350-edb4-49c9-b593-d223f7449a82