Tweaking CI with updated GH actions

Author: bcwaldon

.github/workflows/main.yml

@@ -2,7 +2,7 @@ name: ci
 on:
   # Runs on pushes targeting the default branch
   push:
-    branches: ["*"]
+    branches: ["main"]
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
@@ -33,7 +33,7 @@ jobs:
         run: docker run -v $(pwd):/workspace -w /workspace builder:latest doxygen Doxyfile
 
       - name: upload docs artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: docs
           path: docs/
@@ -46,7 +46,7 @@ jobs:
       name: docs
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
-    - uses: actions/download-artifact@master
+    - uses: actions/download-artifact@v4
       with:
         name: docs
         path: .