Use GitHub Pages official deploy action

[bact]

• Fix Pages deploy by switch to official GitHub Pages deploy action
  • This approach deploy pages directly without writing to a branch (gh-pages), so it will not need any branch permission.
• Remove the tags_file option, which is no longer supported in new version of Material for MkDocs

With this change, the Pages setting should have the source comes from GitHub Actions:

[goneall]

Updated the actions source - here's the current config:

[bact]

Thank you. The new setting should work with this PR (once merge).

[goneall]

LGTM

[goneall]

This worked - the page is now live at https://spdx.github.io/using/

I'll delete the gh-pages branch

[bact]

Thank you. We may add the URL
https://spdx.github.io/using/ to the repo description (on the right pane of the repo page), so people can know the website URL.

[goneall]

Thank you. We may add the URL https://spdx.github.io/using/ to the repo description (on the right pane of the repo page), so people can know the website URL.

Done