try nixpkgs/nix-flakes docker container

.gitea/workflows/nix-flake-check.yaml

@@ -4,18 +4,8 @@ on: push
 jobs:
   nix-flake-update:
     runs-on: ubuntu-latest
+    container: nixpkgs/nix-flakes
     steps:
       - uses: actions/checkout@v4
-      - name: Install Nix
-        run: |
-          sh <(curl -L https://nixos.org/nix/install) --no-daemon --no-channel-add
-          mkdir -p ~/.config/nix
-          touch ~/.config/nix/nix.conf
-          echo "max-jobs = auto" >> ~/.config/nix/nix.conf
-          echo "cores = 0" >> ~/.config/nix/nix.conf
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
-          echo "/nix/var/nix/profiles/per-user/$USER/profile/bin" >> "$GITHUB_PATH"
-          echo "/nix/var/nix/profiles/default/bin" >> "$GITHUB_PATH"
       - name: Check flake
-        run: nix flake check --all-systems
-
+        run: nix flake check