Install node in container; try to help actions find it

One possible problem is that this is actually the downstream Debian
build of Node 18, which may have security patches, but which does
not have any features or breaking changes new in Node 20, and also
which will not report itself as being Node 20.

(GitHub Actions switched from Node 16 to Node 20, so I don't think
using older actions versions would necessarily help.)

.github/workflows/ci.yml

@@ -204,7 +204,9 @@ jobs:
       - name: Prerequisites
         run: |
           apt-get update
-          apt-get install --no-install-recommends -y build-essential ca-certificates cmake curl git jq libssl-dev pkgconf
+          apt-get install --no-install-recommends -y build-essential ca-certificates cmake curl git jq libssl-dev nodejs pkgconf
+          mkdir -p /__e/node20/bin
+          ln -s /usr/bin/node /__e/node20/bin/node
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with: