Editor: Bump pinned hash for the Gutenberg repository.

This updates the pinned hash from the `gutenberg` from `f4d8a5803aa2fbe26e7d9af4d17e80a622b7bab8` to `7b7fa2bc97a8029a302bd6511cf0d206b5953172`.

The following changes are included:

- Sort registry files by handle/ID. (https://github.com/WordPress/gutenberg/pull/75755)
- Obey undoIgnore flag in editEntityRecord (https://github.com/WordPress/gutenberg/pull/76206)
- RTC: Fix `post-editor-template-mode` E2E test (https://github.com/WordPress/gutenberg/pull/76209)
- Publish built Gutenberg plugin to the GitHub Container Registry (https://github.com/WordPress/gutenberg/pull/75844) (https://github.com/WordPress/gutenberg/pull/76273)
- Connectors: Improve placeholder text and make it translatable (https://github.com/WordPress/gutenberg/pull/75996)
- Block context menu: context menu not closing for disconnecting unsynced pattern menu items (https://github.com/WordPress/gutenberg/pull/75405)
- Connectors: Improve responsive layout for small viewports (https://github.com/WordPress/gutenberg/pull/76231)
- theme.json schema: fix pseudo-class definition for button block (https://github.com/WordPress/gutenberg/pull/76272)
- Navigation block: fix submenu chevron toggle on touch devices (https://github.com/WordPress/gutenberg/pull/76197)

See #64595, #64393.

git-svn-id: https://develop.svn.wordpress.org/trunk@61868 602fd350-edb4-49c9-b593-d223f7449a82