🐛 Fix JSON Schema for dataclasses, supporting the fixes in Pydantic 1.9

[PrettyWood]

With model

@dataclass
class Item:
    name: str
    price: float
    tags: List[str] = field(default_factory=list)
    description: Optional[str] = None
    tax: Optional[float] = None

only name and price should be required

⚠️ needs pydantic/pydantic#2557

[codecov]

Codecov Report

Merging #4272 (9b7d120) into master (0a87bc8) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #4272   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          409       409           
  Lines        10264     10270    +6     
=========================================
+ Hits         10264     10270    +6     

Impacted Files	Coverage Δ
...test_tutorial/test_dataclasses/test_tutorial002.py	100.00% <100.00%> (ø)

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[tiangolo]

Amazing, thanks for all your work with Pydantic! 🚀🙇

I updated it to make it pass tests now with the current version and also with the next, that way I can merge it right away. I already made a release (0.70.1) just to unblock you there on the Pydantic PR.