[dataclasses-json] Dict型のプロパティに文字列を設定しようとすると、"TypeError: Type List cannot be instantiated; use list() instead"が発生した

# 環境
* Python3.10.2
    * dataclasses-json 0.5.7


# 何が起きた？
`dataclasses-json`の`from_dict`関数で、Dict型のプロパティに文字列を設定しようとすると、当たり前ですがエラーが発生します。

```python:bar.py
from dataclasses import dataclass
from dataclasses_json import dataclass_json
from typing import List, Dict, Any


@dataclass_json
@dataclass
class Person:
    name: str
    type: Dict[str, Any]
    """型が間違っている。正しくは`str`型"""


@dataclass_json
@dataclass
class School:
    name: str
    people: List[Person]


d_person = {"name": "Alice", "type": "junior"}
d_school = {"name": "tokyo", "people": [d_person]}

school = School.from_dict(d_school)
print(school)
```


```
vagrant@example:~/Documents/study/python$ python bar.py
Traceback (most recent call last):
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 263, in _decode_generic
    res = _get_type_cons(type_)(xs)
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 317, in <genexpr>
    items = (_decode_dataclass(type_arg, x, infer_missing)
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 201, in _decode_dataclass
    init_kwargs[field.name] = _decode_generic(field_type,
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 254, in _decode_generic
    ks = _decode_dict_keys(k_type, value.keys(), infer_missing)
AttributeError: 'str' object has no attribute 'keys'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/vagrant/Documents/study/python/bar.py", line 24, in <module>
    school = School.from_dict(d_school)
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/api.py", line 72, in from_dict
    return _decode_dataclass(cls, kvs, infer_missing)
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 201, in _decode_dataclass
    init_kwargs[field.name] = _decode_generic(field_type,
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/site-packages/dataclasses_json/core.py", line 265, in _decode_generic
    res = type_(xs)
  File "/home/vagrant/.pyenv/versions/3.10.2/lib/python3.10/typing.py", line 941, in __call__
    raise TypeError(f"Type {self._name} cannot be instantiated; "
TypeError: Type List cannot be instantiated; use list() instead
```

直背的なエラーは`AttributeError`なのですが、間接的に`TypeError`も発生しました。
これは、`dataclasses_json/core.py`の`type_(xs)`で、`typing.List(...)`を実行しているためです。


なお、"Type List cannot be instantiated; use list() instead"のメッセージに従って、`people`の型を`typing.List[Person]`から`list[Person]`に変更すると、エラーは発生しません。

```
$ python ~/Documents/study/python/bar.py
School(name='tokyo', people=[])
```

ただし、`people`の値は空リストになります。これは正しくありません。またエラーが発生しないので、間違っていることにも気付けません。



# 補足
`School.from_dict`ではなく`School.schema().load`を実行すれば、型が異なるときに`ValidationError`が発生します。

```
school = School.schema().load(d_school)
# ValidationError: {'people': {0: {'type': ['Not a valid mapping type.']}}}
```

型を意識したコードを書く場合は、`schema().load`を使った方がよさそうです。