Add GitHub token permissions for GitHub Actions workflow

[ceki]

Related issue submitted to SLF4J/logback projects by @varunsh-coder Varun Sharma varunsh@stepsecurity.io

GitHub recommends defining minimum GITHUB_TOKEN permissions for securing GitHub Actions workflows.

See:
GitHub Actions: Control permissions for GITHUB_TOKEN
About the GITHUB_TOKEN secret

The Open Source Security Foundation (OpenSSF) Scorecards treats not setting token permissions as a high-risk issue

[ceki]

Fixed in baf4eab