[FEAT]: Support `sha_pinning_required` for Actions permissions

[sheeeng]

Describe the need

See https://github.blog/changelog/2025-08-15-github-actions-policy-now-supports-blocking-and-sha-pinning-actions/#enforce-sha-pinning.

REST API endpoints for GitHub Actions permissions - GitHub Docs:

https://docs.github.com/en/rest/actions/permissions?apiVersion=2022-11-28#get-github-actions-permissions-for-an-organization
https://docs.github.com/en/rest/actions/permissions?apiVersion=2022-11-28#set-github-actions-permissions-for-an-organization
https://docs.github.com/en/rest/actions/permissions?apiVersion=2022-11-28#get-github-actions-permissions-for-a-repository
https://docs.github.com/en/rest/actions/permissions?apiVersion=2022-11-28#set-github-actions-permissions-for-a-repository

See google/go-github#3808..

SDK Version

No response

API Version

No response

Relevant log output

Code of Conduct

• I agree to follow this project's Code of Conduct

[stevehipwell]

This is blocked until we're using go-github v78+.