Merge pull request #204 from Zsailer/docs-env

update doc requirements

Author: Zsailer

docs/doc-requirements.txt

@@ -1,16 +1,15 @@
 name: jupyter_server_docs
 dependencies:
-- python=3.5
-- sphinx_rtd_theme
-- jinja2
-- tornado
-- nbformat
-- jupyter_client
-- ipykernel
-- sphinx
+- python=3.7
 - pip:
+  - jinja2
+  - tornado
+  - jupyter_client
+  - ipykernel
+  - nbformat
   - Send2Trash
   - prometheus_client
   - sphinxcontrib_github_alt
   - sphinxcontrib-openapi
-  - sphinxemoji
+  - sphinxemoji
+  - git+https://github.com/pandas-dev/pydata-sphinx-theme.git@master