This update for gn fixes the following issues:

- Update to version 0.20260429:
  * Run update reference in CI
  * Add `gn suggest` subcommand.
  * Update documentation
  * [apple] Optimise enumeration of additional files for Xcode project
  * [gn] Split SOURCE_SET phony targets to exclude additional outputs from linking
  * Run formatter in CI
  * Rework update_reference.sh to run correctly in CI.
  * IWYU: gn/target.h
  * Revert "Run formatter and update reference in CI"
  * Revert "Fix: Ensure only actual object files are included in link inputs"
  * Run formatter and update reference in CI
  * Add --diff to run_formatter and update_reference
  * Fix: Ensure only actual object files are included in link inputs
  * Run `infra/recipes.py test train`.
  * Improve EXPECT_EQ diff printing
  * Simplify success expectations in GN.
  * Add support for c_additional_outputs in config
  * Add diffs to EXPECT_EQ.
  * Advertise QtCreator v20+ built-in GN support
  * Rename impl:$MODULE to $MODULE_Private.
  * Only output -fmodule-map-file for the root generated modulemap.
  * Add function `expand_directory` to gn.
  * Refactor ModuleType from an enum to a bitset.
  * Generate two modulemaps per target.
  * Put dependencies in modulemaps
  * Run formatter
  * Include your own modulemap files in module_deps_no_self.
  * Change default module name in GN to be the full label.