Remove unneeded ci config (#227)

Author: chenglou

.github/workflows/ci.yml

@@ -46,7 +46,6 @@ jobs:
       uses: avsm/setup-ocaml@v1.1.10
       with:
         ocaml-version: 4.06.1
-        ocaml-compiler: 4.06.1
 
     - name: Use Node.js
       uses: actions/setup-node@v2.1.5