ci: pr_metadata_check: run the script in unbuffered mode

Makes it easier to debug since there's stuff handling race conditions
now.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

Author: fabiobaltieri

.github/workflows/pr_metadata_check.yml

@@ -36,4 +36,4 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          ./scripts/ci/do_not_merge.py -p "${{ github.event.pull_request.number }}"
+          python -u scripts/ci/do_not_merge.py -p "${{ github.event.pull_request.number }}"