CI/AUTO: SHA Pinning and Dependabot

[ZLLentz]

SHA Pinning

We are now required to pin GitHub Actions to specific SHAs.
This PR automatically updates all actions to a somewhat recent SHA.
It also configures dependabot to update the SHAs for us on a monthly basis.

If this PR is not merged, all GitHub Actions Workflows in this repository
will stop working at the end of June 2026.

See https://jira.slac.stanford.edu/browse/ECS-10557

Code Review

For reviewers: our task is to pick one of:

• Merge as-is, then fix the CI if needed
• Fix the CI, and then merge
• Close this PR and archive the repo
• Merge this PR and archive the repo
• Remove the GitHub Actions configuration from the repo,
  then close this PR.
• Ignore this PR until we use the repo again

[KaushikMalapati]

Not sure if this is still used

[ZLLentz]

it's a good catch, let me remind myself which tools use this

[ZLLentz]

This is at least used in the elog module so we're on the hook for keeping it alive

[ZLLentz]

I think the diff looks normal and the CI passed so let's get it in