Add nodejs to the CI image

The runner executes JavaScript actions (checkout, cache) with node from
inside the job container, so custom container images must provide it.

Dockerfile

@@ -21,6 +21,7 @@ RUN TZ=America/Los_Angeles DEBIAN_FRONTEND=noninteractive apt-get install -y \
     llvm \
     mold \
     ninja-build \
+    nodejs \
     pre-commit \
     python3-requests \
     rpm \