fix doc build

Author: jlwalke2

.github/workflows/build-test-deploy.yml

@@ -71,7 +71,7 @@ jobs:
         run: |
           mv doc docs
           sudo apt-get install build-essential
-          pip install sphinx six
+          pip install sphinx six pyyaml
 
       - name: Check documentation
         uses: ammaraskar/sphinx-problem-matcher@master