[gitla-ci] Add missing reference

.gitlab-ci.yml

@@ -30,3 +30,4 @@ conda-package:
   before_script:
     # for opencv-python dependence
     - if [ "$TAG" == "docker" ]; then apt-get update && apt-get install -y libgl1-mesa-glx > /dev/null; fi
+    - !reference [.snippets, conda-prepare]