Allow empty sub-classes with pydantic-types

[movabo]

Allow the empty inheritance of classes with the pydantic-type decorator as discussed in #1533

Description

Currently, when trying to inherit from a class which was wrapped by strawberry.experimental.pydantic.type or -.input without any additional class variables with the strawberry.auto-annotation, a strawberry.experimental.pydantic.exceptions.MissingFieldsListError arises.

This PR allows the follwing code which would otherwise result in the abovementioned exception:

import strawberry
from strawberry import auto

from pydantic import BaseModel


class NoteModel(BaseModel):
    confidential: str  # do not expose via graphql
    headline: str
    text: str


@strawberry.experimental.pydantic.input(NoteModel)
class NoteInput:
    headline: auto
    text: auto


@strawberry.experimental.pydantic.type(NoteModel)
class Note(NoteInput):
    pass

Completely empty types are still not allowed and would yield an error.

Types of Changes

• [ ] Core
• [x] Bugfix
• [ ] New feature
• [x] Enhancement/optimization
• [ ] Documentation

Issues Fixed or Closed by This PR

• Resolves #1533

Checklist

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[botberry]

Thanks for adding the RELEASE.md file!

Here's a preview of the changelog:

---

Allow empty sub-classes with pydantic-types according to #1533.

---

Here's the preview release card for twitter:

Here's the tweet text:

🆕 Release (next) is out! Thanks to Moritz Bock for the PR 👏

Get it here 👉 https://github.com/strawberry-graphql/strawberry/releases/tag/(next)

[codecov[bot]]

Codecov Report

Merging #1620 (5d9111d) into main (f519299) will increase coverage by 0.00%. The diff coverage is 100.00%.

:exclamation: Current head 5d9111d differs from pull request most recent head 80640f6. Consider uploading reports for the commit 80640f6 to get more accurate results

@@           Coverage Diff           @@
##             main    #1620   +/-   ##
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  Coverage   98.14%   98.14%           
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  Files         129      129           
  Lines        4471     4472    +1     
  Branches      759      760    +1     
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+ Hits         4388     4389    +1     
  Misses         43       43           
  Partials       40       40