add capnp and ffmpeg (#4)

.github/workflows/test.yml

@@ -24,6 +24,8 @@ jobs:
       - uses: actions/setup-python@v6
         with:
           python-version: "3.14"
+      - name: Install build dependencies
+        run: ./setup.sh
       - name: Build wheels
         run: |
           for pkg in */pyproject.toml; do