fix: remove NixOS setup and streamline buildah and podman installation

Signed-off-by: Uwe Hermann <uh@uleenucks.de>

.gitea/workflows/test_build_and_push.yaml

@@ -20,8 +20,7 @@ jobs:
   buildpush:
     name: build_and_push
     needs: [test_shellcheck]
-    #runs-on: [self-hosted, nixos]  # For NixOS runners
-    runs-on: ubuntu-latest     # For Ubuntu runners
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         image:
@@ -38,15 +37,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup NixOS environment
+      - name: Install buildah and podman
         run: |
-          # Ensure buildah and podman are available
-          export PATH="/run/wrappers/bin:/run/current-system/sw/bin:/nix/var/nix/profiles/default/bin:$PATH"
-          echo "PATH=$PATH" >> $GITHUB_ENV
-          
-          # Verify tools are available
-          which buildah || echo "buildah not found in PATH"
-          which podman || echo "podman not found in PATH"
+          apk update
+          apk add --no-cache buildah podman
 
       - name: Build ${{ matrix.image.name }} image
         id: build