[ci] update submodule

.gitlab-ci.yml

@@ -22,6 +22,7 @@ doc:
     - python --version
     - python -m pip install pip --upgrade
     - python -m pip install setuptools --upgrade
+    - git submodule update --init --recursive
     - rm -rf artifacts
     - mkdir artifacts
   script:
@@ -44,6 +45,7 @@ doc:
     - python --version
     - python -m pip install pip --upgrade
     - python -m pip install setuptools --upgrade
+    - git submodule update --init --recursive
   script:
     - python -m pip install .
     - python run_tests.py -v