build: Update GutenbergKit ref

Author: dcalhoun

Modules/Package.swift

@@ -47,7 +47,7 @@ let package = Package(
         .package(url: "https://github.com/zendesk/support_sdk_ios", from: "8.0.3"),
         // We can't use wordpress-rs branches nor commits here. Only tags work.
         .package(url: "https://github.com/Automattic/wordpress-rs", revision: "alpha-swift-20240813"),
-        .package(url: "https://github.com/wordpress-mobile/GutenbergKit", revision: "849118af582068f75807bc0f1265edeee4bf1b5e"),
+        .package(url: "https://github.com/wordpress-mobile/GutenbergKit", revision: "e76e6f38641b886a85c470ded4cf816e161c50b1"),
         .package(url: "https://github.com/Automattic/color-studio", branch: "trunk"),
     ],
     targets: XcodeSupport.targets + [