ci experiment: pin livekit-server to 1.13.2

Tests whether the test_audio sine-frequency flake (first seen 2026-07-09)
correlates with the livekit-server 1.13.3 release (2026-07-03). Do not merge.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: 1egoman

.github/workflows/tests.yml

@@ -151,6 +151,9 @@ jobs:
         uses: livekit/dev-server-action@61e2b4dcb170dd3591e0c9b0db3c3fe5db93b500
         with:
           github-token: ${{ github.token }}
+          # CI experiment: pin the server to the last pre-1.13.3 release to
+          # test whether the test_audio flake correlates with the server bump.
+          version: 1.13.2
           config: |
             # TODO: Remove once this is enabled by default.
             enable_participant_data_blob: true