ci: remove nix flake check run...

...we'll re-introduce specific pure tests later on, but nix flake check
always evaluates packages for all platforms as far as we know, and
that will fail if not all lock files are up to date

.github/workflows/tests.yml

@@ -5,25 +5,6 @@ on:
 
 jobs:
 
-  tests-pure:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/[email protected]
-    - uses: cachix/install-nix-action@v22
-      with:
-        install_url: https://nixos-nix-install-tests.cachix.org/serve/8i0c4nnvddybdq6a684ffybc5p7ziif0/install
-        install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'
-        extra_nix_config: |
-          access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
-          max-jobs = 10
-    - uses: cachix/cachix-action@v12
-      with:
-        name: nix-community
-        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-
-    - run: |
-        nix flake check
-
   tests-format:
     runs-on: ubuntu-latest
     steps: