Fix PEP 0673 before 3.11

[george-zubrienko]

Fixes #459

Working example on 3.10

from dataclasses_json import dataclass_json
@dataclass_json
@dataclass
class SpecialLinkedList:
    val: int
    nexts: list['SpecialLinkedList'] = None

my_list = SpecialLinkedList(val=1, nexts=[SpecialLinkedList(val=2)])
print(SpecialLinkedList.from_dict(my_list.to_dict()))
print(my_list)

SpecialLinkedList(val=1, nexts=[SpecialLinkedList(val=2, nexts=None)])
SpecialLinkedList(val=1, nexts=[SpecialLinkedList(val=2, nexts=None)])

Approach

Since before 3.10 we get the type as a plain string, and it is not a fully-qualified import reference, the only option I see is to go over all imported modules and try find the type string there. If that fails, we admit the failure and print a warning to the use saying expected outcome will not the as expected. This code only runs for versions <3.11

[george-zubrienko]

Will finalize this week - sorry for all the waiting, tough times.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
dataclasses_json
cfg.py	51	4	92%	80, 84–86
core.py	258	17	93%	39–42, 52, 65, 67, 82, 84, 170, 198, 378–385, 389
mm.py	205	30	85%	33–36, 42–45, 53–56, 62–65, 88, 170–171, 176, 180, 184, 189, 193, 197, 205, 211, 216, 225, 230, 235, 244, 253–260
stringcase.py	25	3	88%	59, 76, 97
undefined.py	146	2	99%	25, 39
utils.py	131	36	73%	12–25, 45–50, 61–65, 75, 100–101, 109–110, 125–133, 163, 182, 207
tests
entities.py	239	3	99%	22, 234, 240
test_annotations.py	81	42	48%	50–67, 78–102, 106–122
test_api.py	142	4	97%	88, 99, 139–140
test_str_subclass.py	22	1	95%	9
test_union.py	131	10	92%	97–104, 118–125
TOTAL	2645	152	94%

Tests	Skipped	Failures	Errors	Time
305	3 💤	0 ❌	0 🔥	6.249s ⏱️

[matt035343]

LGTM