ci: Remove nix check from the critical path in ci.yaml

.github/workflows/ci.yaml

@@ -677,24 +677,6 @@ jobs:
           cat config.vars
           VALGRIND=0 uv run eatmydata pytest tests/ ${GLOBAL_PYTEST_OPTS} -n ${PYTEST_PAR} ${PYTEST_OPTS}
 
-  check-flake:
-    name: Check Nix Flake
-    runs-on: ubuntu-22.04
-    strategy:
-      fail-fast: true
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-      - name: Check Nix flake inputs
-        uses: DeterminateSystems/flake-checker-action@v8
-      - name: Install Nix
-        uses: cachix/install-nix-action@v31
-        with:
-          nix_path: nixpkgs=channel:nixos-unstable
-      - name: Check flake
-        run: nix flake check
 
   gather:
     # A dummy task that depends on the full matrix of tests, and