set single-commit=true for doc branch

see if this clears the commit history. Fixes #583

Author: jacobwilliams

.github/workflows/CI.yml

@@ -150,6 +150,7 @@ jobs:
       with:
         branch: gh-pages # The branch the action should deploy to.
         folder: doc  # The folder the action should deploy.
+        single-commit: true
         clean: true
         clean-exclude: |
           prev
@@ -166,7 +167,7 @@ jobs:
 
     - name: Deploy documentation for tagged release
       if: matrix.gcc_v == 7 && startsWith(github.ref, 'refs/tags/')
-      uses: JamesIves/github-pages-deploy-action@v4.6.1
+      uses: JamesIves/github-pages-deploy-action@v4.7.3
       with:
         branch: gh-pages # The branch the action should deploy to.
         folder: doc  # The folder the action should deploy.