workflows: update workflow actions (#29)

Update the workflow actions used in hugo.yml.

GitHub Actions emits some warnings regarding Node 16 deprecation and
recommends updating the workflows to the latest version running on Node
20.

Signed-off-by: Luca Zeuch <[email protected]>

.github/workflows/hugo.yml

@@ -25,18 +25,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Install Hugo
-        uses: peaceiris/actions-hugo@v2
+        uses: peaceiris/actions-hugo@v3
         with:
           hugo-version: latest
           # We use the extended version just to be on the safe side.
           # It is recommended anyway.
           extended: true
 
       - name: Cache Hugo modules
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ${{ env.HUGO_CACHEDIR }}
           key: ${{ runner.os }}-hugomod-${{ hashFiles('**/go.sum') }}
@@ -55,7 +55,7 @@ jobs:
 
       - name: Upload artifact
         if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: ./public