Filter out the author when dispatching reviewers

```yaml - name: request for review run: | # request two reviewers from OWNERS file randomly PR_NUMBER=${{ github.event.pull_request.number }} REVIEWERS=$(yq '.reviewers[]' OWNERS | shuf | head -n 2 | paste -sd ",") gh pr edit $PR_NUMBER --add-reviewer $REVIEWERS ``` Right now, when dispatching reviewers, we'll not filter out the author if he's one of the reviewers, which may lead to only one reviewer requested.