fix: pull updated gh-pages (#200)

Hotfix to #196 that automates GitHub Pages deployments. Looks like the
workflow failed in error because it didn't have the most recent version
of the gh-pages branch. This PR will hopefully fix that issue.

Signed-off-by: Jacob Emery <jacob.emery@ibm.com>

.github/workflows/main.yaml

@@ -16,12 +16,20 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: main
+          fetch-depth: 0
 
       - name: Setup Python
         uses: actions/setup-python@v2
         with:
           python-version: '3.x'
 
+    - name: Fetch Latest gh-pages Branch
+      run: |
+        git fetch origin gh-pages
+        git checkout gh-pages
+        git pull origin gh-pages
+        git checkout main
+
       - name: Install mkdocs
         run: pip install mkdocs