.yaml files missing from .gitattributes

[tzturner]

Context

I believe cleanup.yaml and pr_reminder.yaml should be in the .gitattributes list.

It should also include detect_secrets.yaml, which should also be added to this repository

Tasks

• copy in secret detection yaml from https://github.com/techservicesillinois/SecOps-Tools/blob/main/.github/workflows/detect-secrets.yaml
• update .gitattributes to include lines for the three yaml files