separate install?

Author: anmonteiro

.github/workflows/opam-build.yml

@@ -53,9 +53,16 @@ jobs:
       - name: Install dependencies (Windows)
         if: ${{ matrix.os == 'windows-latest' }}
         working-directory: melange
-        run: opam update
+        run: |
+          opam update
+          opam pin -y add dune.dev https://github.com/ocaml/dune.git#a08e0f7f8a857b348267b30b10b9297ef881bb4d
+          opam pin -y add melange-compiler-libs.dev https://github.com/melange-re/melange-compiler-libs.git#575ac4c24b296ea897821f9aaee1146ff258c704
+          opam pin add reactjs-jsx-ppx.dev . --with-test -y
+          opam pin add melange.dev . --with-test -y
+          opam pin add rescript-syntax.dev . --with-test -y
 
       - name: Install dependencies
+        if: ${{ matrix.os != 'windows-latest' }}
         working-directory: melange
         run: |
           opam update