updated gitlab-ci to install requirements before building the documentation....

I believe the problem with autodoc constructing the documentation was caused by missing dependencies. This merge request install all pyicon dependencies before attempting to build the documentation.

.gitlab-ci.yml

 pages:
   script:
   - conda env create -f ci/requirements_py311.yml
-  - conda activate pyicon_py311
+  - source activate pyicon_py311
   - pip install -e .
   - cd doc
   - make html