Update .github/workflows/ci.yaml

We want to have an additional step where the deployment requires manual
approval so we should add environment property.

Co-authored-by: Jakub Nowakowski <jakub.nowakowski@keep.network>

.github/workflows/ci.yaml

@@ -75,6 +75,9 @@ jobs:
     name: Deploy
     needs: build
     if: github.event_name == 'push'
+    # production environment is protected, it requires an approval before execution.
+    environment:
+      name: prod
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2