Fix detection of github organization for README templates

[osterman]

what

• Use the github_repo parameter in the README.yaml to determine the organization
• Make git checkout safe for linters to use
• Update uses of actions/checkout to v4

why

• Use Organization's .github README.md.gotmpl #368 introduce the ability to have readme's sourced from various organizations
• It did not take into account that the git remotes for forks will give the organization of the fork
• It's better to use the README.yaml to determine the org, but this was not considered in the original implementation

references

• Use Organization's .github README.md.gotmpl #368
• Restore README_INCLUDES #371
• fatal: unsafe repository (REPO is owned by someone else) in other workflow steps after running checkout actions/checkout#766