Fix cachix push

.github/workflows/cachix.yml

@@ -26,5 +26,6 @@ jobs:
 
       - name: Build and Push with Cachix
         run: |
+          nix develop
           set -e
-          nix build | cachix push larstvei
+          nix build --json | jq -r '.[].outputs | to_entries[].value' | cachix push larstvei

flake.nix

@@ -43,5 +43,7 @@
           extraEmacsPackages = epkgs:
             [ epkgs.treesit-grammars.with-all-grammars ];
         };
+
+        devShell = pkgs.mkShell { buildInputs = [ pkgs.jq ]; };
       });
 }