Update pip install commands in GitLab CI configuration

Revised the pip install commands to improve dependency management. Consolidated 'pymumble' installation into a grouped extras requirement '[mumble]'. This ensures better clarity and usage of optional dependencies.

.gitlab-ci.yml

@@ -16,8 +16,8 @@ pages:
   script:
     - apt-get update -qy
     - apt-get install -y python3-dev python3-pip graphviz graphviz-dev portaudio19-dev
-    - pip install pdoc pymumble
-    - pip install .
+    - pip install pdoc
+    - pip install '.[mumble]'
     - pdoc --output-dir public cooperative_cuisine !cooperative_cuisine.reinforcement_learning !cooperative_cuisine.pygame_2d_vis.performance_benchmark --logo https://gitlab.ub.uni-bielefeld.de/uploads/-/system/project/avatar/6780/Cooking-Vector-Illustration-Icon-Graphics-4267218-1-580x435.jpg --docformat google --favicon cooperative-cuisine/cooperative_cuisine/pygame_2d_vis/images/favicon.ico --footer-text "Developed@SCS"
   artifacts:
     paths: