Do explicit checkout

.github/workflows/github_action_build_docs.yml

@@ -38,6 +38,8 @@ jobs:
 
       - name: Install doc-building dependencies
         run: |
+          git branch 
+          git checkout develop
           python -m pip install --upgrade pip
           cd docs/
           make install

docs/Makefile

@@ -3,7 +3,6 @@
 SOURCEDIR     = source
 BUILDDIR      = build
 AUTODOCDIR = $(SOURCEDIR)/api
-#
 # You can set these variables from the command line, and also
 # from the environment for the first two.
 SPHINXOPTS    ?=