DOC/MNT install docs with dev version of sphinx theme

Author: jklymak

.circleci/config.yml

@@ -100,6 +100,13 @@ commands:
                 numpy<< parameters.numpy_version >> codecov coverage \
                 -r requirements/doc/doc-requirements.txt
 
+  mpl-theme-install:
+    steps:
+      - run:
+          name: Install mpl-sphinx-theme dev
+          command: |
+            pip install git+https://github.com/matplotlib/mpl-sphinx-theme.git
+
   mpl-install:
     steps:
       - run: