fix workflow

Author: yuyuyureka

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
         name: wobcom-public
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - run: 'nix build .#${{ matrix.packageset }}.fernglas -vL'
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: '${{ matrix.packageset }}.fernglas'
         path: result/bin/fernglas
@@ -39,7 +39,7 @@ jobs:
     - run: nix build .#fernglas-frontend -vL
     # https://github.com/actions/upload-artifact/issues/92
     - run: cp -r result/ result-frontend
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: fernglas-frontend
         path: result-frontend/*