ci(gh-actions): Add missing env variables

Now mcl validates all ci_matrix env vars on startup.

.github/workflows/ci.yml

@@ -74,6 +74,8 @@ jobs:
       - name: Generate Matrix for Matrix
         id: generate-matrix
         env:
+          CACHIX_CACHE: ${{ vars.CACHIX_CACHE }}
+          CACHIX_AUTH_TOKEN: ${{ secrets.CACHIX_AUTH_TOKEN }}
           MCL_BRANCH: ${{ github.repository == 'metacraft-labs/nixos-modules' && github.sha || 'main' }}
         run: nix run --accept-flake-config github:metacraft-labs/nixos-modules/${{ env.MCL_BRANCH }}#mcl shard_matrix
     outputs: