Update docker.yml

Author: danyaberezun

.github/workflows/docker.yml

@@ -34,5 +34,6 @@ jobs:
       - name: List installed packages
         run: opam list
 
+      - run: eval $(opam env)
       - run: opam exec -- dune build --profile=release
       - run: opam exec -- dune test regression/ stdlib/regression