ci: update github actions workflows

[afuetterer]

What does this PR do?

This PR does two things:

• bump the github actions versions
• switch to the smaller ubuntu-slim runner slim for the lint job

Refs:

• https://github.blog/changelog/2025-10-28-1-vcpu-linux-runner-now-available-in-github-actions-in-public-preview/
• https://docs.github.com/en/actions/reference/runners/github-hosted-runners

Before submitting

• This PR fixes a typo or improves the docs (if yes, ignore all other checks!).
• Did you read the contributor guideline?
• Was this discussed/approved via a Github issue? Please add a link to it if that's the case.
• Did you make sure to update the documentation with your changes (if applicable)?
• Did you write any new necessary tests?