field ordering issue causing invalid python models

[robbertvanwaveren]

Describe the bug
Whenever there is a field with some additional metadata like "aliases" or "doc" it causes the generated python field to look like this:

    fieldwithdefault: str = "some default value"
    someotherfield: int = dataclasses.field(metadata={'aliases': ['oldname']})

However these get ordered behind (original order?) fields with a default value which is not valid python. Without aliases or doc these fields do correctly get shifted before fields with defaults.

To Reproduce

{
  "type": "record",
  "name": "Message",
  "fields": [
    {
      "name": "fieldwithdefault",
      "type": "string",
      "default": "some default value"
    },
    {
      "name": "someotherfield",
      "type": "long",
      "aliases": ["oldname"],
      "doc": "test"
    }
  ]
}

Expected behavior
fields get ordered with default values last

    someotherfield: int = dataclasses.field(metadata={'aliases': ['oldname']})
    fieldwithdefault: str = "some default value"