chore: Set permissions for GitHub actions (#898)

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.

- 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/)

Signed-off-by: naveen <172697+naveensrinivasan@users.noreply.github.com>

Author: naveensrinivasan

.github/workflows/ci.yml

@@ -16,6 +16,9 @@ env:
   GRADLE_OPTS: '-Dorg.gradle.daemon=false -Dorg.gradle.java.installations.auto-detect=false -Dorg.gradle.warning.mode=fail'
   CMAKE_VERSION: '3.14.7'
 
+permissions:
+  contents: read
+
 jobs:
   java-build:
     name: Java ${{ matrix.java }} (${{ matrix.os }})