CI: upload-pages-artifact v1 -> v3 (fix?)

https://github.com/actions/upload-pages-artifact/releases/tag/v3.0.1

Bump actions/checkout from 3 to 4 @dependabot (#76)

CI currently broken:

https://github.com/lem-project/lem-project.github.io/actions/runs/13651737904

build:
This request has been automatically failed because it uses a deprecated version of `actions/upload-artifact: v3`. Learn more: https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/

Author: vindarel

.github/workflows/hugo.yml

@@ -58,7 +58,7 @@ jobs:
             --minify \
             --baseURL "${{ steps.pages.outputs.base_url }}/"
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v3
         with:
           path: ./public