CI: Drop sphinxcontrib packages

There are no such conda packages

Author: sebp

environment.yml

@@ -9,11 +9,6 @@ dependencies:
   - pillow
   - pip
   - sphinx<4
-  - sphinxcontrib_applehelp<1.0.5
-  - sphinxcontrib_devhelp<1.0.3
-  - sphinxcontrib_htmlhelp<2.0.2
-  - sphinxcontrib_qthelp<1.0.4
-  - sphinxcontrib_serializinghtml<1.1.6
   - sphinx_rtd_theme<2
   - pip:
     - sphinx-intl