Set permissions for GitHub actions (#14693)

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

https://www.legitsecurity.com/blog/github-privilege-escalation-vulnerability

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

.github/workflows/iam-integrations.yaml

@@ -11,6 +11,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 jobs:
   iam-matrix-test:
     name: "[Go=${{ matrix.go-version }}|ldap=${{ matrix.ldap }}|etcd=${{ matrix.etcd }}|openid=${{ matrix.openid }}]"