nixos: disable github-ci build of nixos

I tested that make docker-build-nix works locally, but it fails in
the github-ci environment with permission errors:
```
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.6471719Z building '/nix/store/25ijc05ya70h07i9569jm8r61j49bqw9-katzen-unstable-20240920073414-go-modules.drv'...
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9374960Z error: builder for '/nix/store/25ijc05ya70h07i9569jm8r61j49bqw9-katzen-unstable-20240920073414-go-modules.drv' failed with exit code 1;
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9376414Z        last 4 log lines:
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9377148Z        > Running phase: unpackPhase
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9378227Z        > unpacking source archive /nix/store/c30a1mz53jx5mbp2m5rk93745i2pv62h-source
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9379423Z        > cp: setting permissions for 'source': Operation not permitted
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9380851Z        > do not know how to unpack source archive /nix/store/c30a1mz53jx5mbp2m5rk93745i2pv62h-source
build_other_linuxes	Build for Nix	2024-09-20T07:36:33.9382876Z        For full logs, run 'nix log /nix/store/25ijc05ya70h07i9569jm8r61j49bqw9-katzen-unstable-20240920073414-go-modules.drv'.
build_other_linuxes	Build for Nix	2024-09-20T07:36:34.0858793Z error: 1 dependencies of derivation '/nix/store/89gffkm0fljnwal2f478bq6ma9m7fqal-katzen-unstable-20240920073414-env.drv' failed to build
build_other_linuxes	Build for Nix	2024-09-20T07:36:36.2549473Z make: *** [Makefile:59: docker-nix-base.stamp] Error 1
build_other_linuxes	Build for Nix	2024-09-20T07:36:36.2566840Z ##[error]Process completed with exit code 2.

```

this commit disables github-ci for nixos because I don't have any more time to debug this.

.github/workflows/go.yml

@@ -31,17 +31,17 @@ jobs:
           name: katzen.alpine
           path: ./katzen
 
-      - name: Build for Nix
-        run: make docker-build-nix
+      #- name: Build for Nix
+      #  run: make docker-build-nix
 
-      - name: Save output artifact name
-        run: ls nix_build | head -1 > nixos.output
+      #- name: Save output artifact name
+      #  run: ls nix_build | head -1 > nixos.output
 
-      - name: Upload binary artifact
-        uses: actions/upload-artifact@v4
-        with:
-          name: nixos.output
-          path: nixos.output
+      #- name: Upload binary artifact
+      #  uses: actions/upload-artifact@v4
+      #  with:
+      #    name: nixos.output
+      #    path: nixos.output
 
   build_windows:
     runs-on: ubuntu-22.04
@@ -136,16 +136,16 @@ jobs:
         with:
           name: katzen-macos-arm64
 
-      - name: Download nixos output name
-        uses: actions/download-artifact@v4
-        with:
-          name: nixos.output
+      #- name: Download nixos output name
+      #  uses: actions/download-artifact@v4
+      #  with:
+      #    name: nixos.output
 
       - name: Hash and commit
         run: |
           sha256sum katzen katzen.apk katzen-macos-arm64 katzen-macos-amd64 katzen.exe > katzen.sha256
-          echo -n "# the nixos output was: " >> katzen.sha256
-          cat nixos.output >> katzen.sha256
+     #     echo -n "# the nixos output was: " >> katzen.sha256
+     #     cat nixos.output >> katzen.sha256
 
       - name: Create release
         id: create_release