Build/Test Tools: Update Gutenberg hash to fix CSS minification.

Updates the Gutenberg ref to include changes that generate both minified and non-minified CSS files during build. Previously, the build only produced a single CSS file (e.g., `style.css`), causing missing asset errors when `SCRIPT_DEBUG` is set to `false`, as Core expects `.min.css` files.

Props peterwilsoncc, dd32, tyxla, jsnajdr, mcsf.
Fixes #64393.


git-svn-id: https://develop.svn.wordpress.org/trunk@61446 602fd350-edb4-49c9-b593-d223f7449a82

Author: youknowriad

package.json

@@ -7,7 +7,7 @@
 		"url": "https://develop.svn.wordpress.org/trunk"
 	},
 	"gutenberg": {
-		"ref": "b79bbe25a1b00ce640bfab363f182c678181082f"
+		"ref": "dea73b609a80016eb1cf3893ea183fe106a06740"
 	},
 	"engines": {
 		"node": ">=20.10.0",