list/check docs env

Author: bollwyvl

.github/workflows/ci.yml

@@ -92,13 +92,14 @@ jobs:
         with:
           node-version: 14.x
       - name: Install package and docs dependencies
-        # run: |
-        #  set -eux
-        #  pip install -vv -U .[docs,examples,test] requests_cache 'traitlets==4.*'
-        # TODO: uncomment above, remove below to get docs to build, add link to issue
         run: |
           set -eux
-          pip install -vv -U .[docs,examples,test] requests_cache
+          pip install -vv -U -e .[docs,examples,test] requests_cache
+      - name: Validate docs environment
+        run: |
+          set -eux
+          pip freeze
+          pip check
       - name: Build docs
         run: |
           set -eux