build: clean up and document CMake file

Issue #471

Author: jmcnamara

.github/workflows/code_style.yml

@@ -16,6 +16,8 @@ jobs:
       run: |
         sudo apt-get -y install indent
         sudo ln -s /usr/bin/indent /usr/bin/gindent
+        python -m pip install --upgrade pip
+        pip install gersemi
 
     - name: Make indent
       run: |