Fixup: windows10.json syntax error

Packer/windows_10.json

@@ -190,6 +190,4 @@
     "autounattend_virtio": "./answer_files/10_virtio/Autounattend.xml",
     "packer_build_dir": "/media/packer_build_dir/win10"
   }
-}
-  }
 }