Add specific permissions to check-dist.yml workflow

[varunsh-coder]

This PR adds token permissions to the check-dist.yml workflow. This is a security best practice as per GitHub and is checked by OSSF Scorecard.

1. I am collating security information about different GitHub Actions in an open-source knowledge-base to calculate minimum GITHUB_TOKEN permissions and restrict outbound traffic to allowed domains. As an owner of actions/checkout Action, please review info about it in the knowledge-base here - specifically the reason for the token permissions the Action needs and expected outbound calls it makes. e.g. the # for actions/checkout to fetch code part in the check-dist.yml file comes from the knowledge base.
2. JFYI - You can easily add token permissions and other security best practices to other workflows in this repo using https://app.stepsecurity.io. It uses the knowledge base mentioned above...Do let me know if you have feedback. Thanks!