Update repository-governance extension to v2.0.6

[bigsmartben]

Summary

• Update bundled repository-governance extension to v2.0.6.
• Update extensions/catalog.json metadata.

Test Plan

• python3 -m py_compile extensions/repository-governance/scripts/refresh_repository_governance.py
• python3 -m pytest -q tests/test_arch_templates.py tests/integrations/test_cli.py::TestGitExtensionOptIn::test_community_extensions_and_workflow_preset_auto_installed tests/integrations/test_cli.py::TestGitExtensionOptIn::test_no_git_keeps_community_defaults
• python3 -m pytest -q tests/test_presets.py -k workflow_preset_integration_release_payload_contract
• python3 -m json.tool extensions/catalog.json >/dev/null