Rolled back environment.yml to use pip install -e .['tests']

Installing EVERYTHING with pip was not a smart idea...

.gitlab-ci.yml

@@ -27,7 +27,8 @@ test:
     # TODO: Different jobs with custom develop arguments? extra_requires (hyperspy, plotting)?
     # TODO: Use pip install -e .[hyperspy], etc.
     # Install requirements:
-    - pip install -r requirements.txt  # TODO: Use conda docker image if available!?
+    # - pip install -r requirements.txt  # TODO: DOES NOT WORK (because mayavi and stuff...)
+    - pip install -e .['tests']
     - python setup.py test
     - coverage html
   artifacts: