fix checkout

.github/workflows/check_encoding.yml

@@ -38,7 +38,7 @@ jobs:
       uses: actions/checkout@v2
       with:
         repository: gabrielhdt/lambdapi
-        branch: refiner
+        ref: refiner
         path: lambdapi
 
     # Runs a set of commands using the runners shell
@@ -46,8 +46,7 @@ jobs:
       run: |
         sudo apt install --yes bmake
         (cd "${GITHUB_WORKSPACE}/lambdapi/" || exit 1
-         opam install . --deps-only
-         make install)
+         opam install .)
         eval $(opam env)
         why3 config detect