[actions] fix missing dependency

.gitea/workflows/update-flake-lock.yml

@@ -13,6 +13,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      - name: Install dependencies for Nix setup action
+        run: |
+          apt update -y
+          apt install sudo -y
       - name: Install Nix
         uses: cachix/install-nix-action@v30
       - name: Update flake.lock