fixes to readme checks

[yshavit]

• fix the workflow name
• fix the job name
• rm the needs dependency
• put in the correct version to the readme (I had previously put an intentionally incorrect one, to prove this script works; and then I forgot to remove it)

In service of (and may resolve) #221

[yshavit]

• Example of a run showing a failure when the readme is incorrect: https://github.com/yshavit/mdq/actions/runs/13582857797
• Example of a run when the readme is correct: https://github.com/yshavit/mdq/actions/runs/13582918913

I put this on a workflow that only runs on merges to main, not at every push to a PR. It's a relatively slow workflow, and I don't think it'll actually change that frequently, so I'm okay with it detecting changes out of band.