Set permissions for GitHub actions (EbookFoundation#6820)

- Included permissions for the action. https://github.com/ossf/scorecard/blob/main/docs/checks.md#token-permissions

https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#permissions

https://docs.github.com/en/actions/using-jobs/assigning-permissions-to-jobs

[Keeping your GitHub Actions and workflows secure Part 1: Preventing pwn requests](https://securitylab.github.com/research/github-actions-preventing-pwn-requests/)

 Restrict the GitHub token permissions only to the required ones; this way, even if the attackers will succeed in compromising your workflow, they won’t be able to do much.

Signed-off-by: naveensrinivasan <[email protected]>

Signed-off-by: naveensrinivasan <[email protected]>

.github/workflows/fpb-lint.yml

@@ -2,6 +2,9 @@ name: free-programming-books-lint
 
 on: [push, pull_request]
 
+permissions:
+  contents: read
+
 jobs:
   build: