ci: fix benchmark

[mmalenic]

Changes

• Use GITHUB_TOKEN to authenticate the benchmark action.
• Update action versions and remove actions-rs as it is no longer maintained.

[brainstorm]

Good catch, I can't recall why I created a custom GH PAT for this... perhaps I wanted to limit the scopes/access that GITHUB_TOKEN has, but it's definitely more practical to use GITHUB_TOKEN as it doesn't expire as fast...

[mmalenic]

I think a similar effect can be achieved by specifying the GITHUB_TOKEN permissions: https://docs.github.com/en/actions/security-guides/automatic-token-authentication#modifying-the-permissions-for-the-github_token