simplify github action

.github/workflows/coverage.yml

@@ -37,28 +37,9 @@ jobs:
         uses: ocaml/setup-ocaml@v2
         with:
           ocaml-compiler: ${{ matrix.ocaml-compiler }}
-          opam-local-packages: $${ matrix.opam-local-packages }}
-          opam-depext-flags: --with-test
-
-      - name: Pin local packages
-        run: |
-          # Pin all local opam files to avoid internal conflicts
-          # 
-          # TODO: replace with `opam pin --with-version` when Opam 2.1 is
-          # available via `setup-ocaml`.
-          opam exec -- ocamlc -config
-          find . -maxdepth 1 -name '*.opam' -printf '%P\n' |\
-              cut -d. -f1 |\
-              xargs -I{} -n 1 opam pin add {}.dev ./ -n
-
-      - name: Install depexts
-        run: |
-          find . -maxdepth 1 -name '*.opam' -printf '%P\n' |\
-             cut -d. -f1 |\
-             xargs opam depext --update -y
 
       - name: Install Opam dependencies
-        run: opam install ${{ matrix.packages }} --with-test --deps-only
+        run: opam install . --with-test --deps-only
 
       - name: Run tests with coverage instrumentation
         run: opam exec -- dune runtest --verbose --instrument-with bisect_ppx