[gitlab-ci] Add missing libgl package when building in docker

.gitlab-ci.yml

@@ -25,3 +25,8 @@ tests:
     # for pytorch quirks on linux
     - if [ "$TAG" == "docker" ]; then export OMP_NUM_THREADS=1; fi # Set the number of threads used to 1
     - !reference [.snippets, test-prepare]
+
+conda-package:
+  before_script:
+    # for opencv-python dependence
+    - if [ "$TAG" == "docker" ]; then apt-get update && apt-get install -y libgl1-mesa-glx > /dev/null; fi