test: see if using an action to isntall nix will work

Signed-off-by: silver <silver@skynet.ie>

.forgejo/workflows/push.yaml

@@ -9,9 +9,12 @@ on:
 
 jobs:
   build:
-    # build it using teh base nixos system, helps with caching
+    runs-on: docker
-    runs-on: nix
     steps:
+      - uses: https://github.com/cachix/install-nix-action@v29
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - run: nix --version
       # get the repo first
       - uses: https://code.forgejo.org/actions/checkout@v4
       # Make sure all files are pulled down