merge gitea & github

.gitea/workflows/update.yaml

@@ -10,9 +10,17 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: ./.actions/init
+
+      - name: Install nix
+        uses: cachix/install-nix-action@v31
         with:
-          token: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - name: Use cachix
+        uses: cachix/cachix-action@v16
+        with:
+          name: trevstack
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       # https://github.com/actions/checkout/issues/13
       - name: Set git config