fix: add pyyaml to pkg-gen pre-commit hook dependencies

The verify_file_secrets_sync function imports yaml.safe_load but pyyaml
was not listed in the pkg-gen hook's additional_dependencies, causing
CI to fail with ModuleNotFoundError.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nathan-weinberg

.pre-commit-config.yaml

@@ -51,6 +51,10 @@ repos:
         pass_filenames: false
         require_serial: true
         always_run: true
+        additional_dependencies:
+          - uv>=0.9.0
+          - ruamel.yaml>=0.18.0
+          - pyyaml>=6.0.2
 
       - id: doc-gen
         name: Distribution Documentation