Update .readthedocs.yaml

.readthedocs.yaml

@@ -15,8 +15,6 @@ build:
 sphinx:
   configuration: source/conf.py
   builder: html
-  extra_requirements:
-    - sphinx_rtd_theme
     
 # We recommend specifying your dependencies to enable reproducible builds:
 # https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html