Fix target to push to Docker Hub

.gitlab-ci.yml

@@ -41,7 +41,7 @@
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
   variables:
-    DOCKERHUB_IMAGE: index.docker.io/v1/ocamlpro/ocaml
+    DOCKERHUB_IMAGE: ocamlpro/ocaml
   script:
   - |
     echo "{
@@ -50,7 +50,7 @@
           \"username\":\"$CI_REGISTRY_USER\",
           \"password\":\"$CI_REGISTRY_PASSWORD\"
         },
-        \"https://index.docker.io/v1/\": {
+        \"index.docker.io": {
           \"auth\":\"$DOCKERHUB_AUTH\"
         }
     }}