nixos/services: add gitea server

nixos/vm.nix

@@ -7,8 +7,8 @@
     memorySize = 4096;
 
     qemu.networkingOptions = lib.mkForce [
-      "-net nic,netdev=user.0,model=virtio"
-      "-netdev user,id=user.0,\${QEMU_NET_OPTS:+,$QEMU_NET_OPTS}"
+      "-nic bridge,br=virbr0,id=hn0,model=virt-net-pci,helper=/run/wrappers/bin/qemu-bridge-helper"
+      "-device virtio-net-pci,netdev=hn0,id=nic1"
     ];
   };
 }