Ensure dependencies for french_law are as tight as possible

See related patch in french_law: running `npm install` would bring in the whole
bs platform, including the recompilation of a full OCaml compiler which takes
>30min on our small runners. In fact for the purpose here, it's not needed so
restrict to just the smallest js requirements.

.github/workflows/harness.yml

@@ -90,7 +90,7 @@ jobs:
       - name: Build french-law
         run: |
           cd ~/french-law
-          opam --cli=2.1 exec -- make dependencies-js dependencies-python
+          opam --cli=2.1 exec -- make dependencies
           opam --cli=2.1 exec -- make all
       - name: Gather all artifacts
         run: |