update checkout action due to depreciation

Author: knarrff

.github/workflows/static.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Setup Pages
         uses: actions/configure-pages@v4
       - run: sudo apt-get install -y python3-matplotlib