Fix broken Any and TypeVar behaviour

[samuelcolvin]

Change Summary

• fix None value passed to Any fields
• support TypeVar and thereby un-parameterized collection types, e.g. Dict rather than Dict[Any, Any]

Related issue number

fix #961

Checklist

• Unit tests for the changes exist
• Tests pass on CI and coverage remains at 100%
• Documentation reflects the changes where applicable
• changes/<pull request or issue id>-<github username>.md file added describing change
  (see changes/README.md for details)

[codecov]

Codecov Report

Merging #962 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #962    +/-   ##
======================================
  Coverage     100%   100%            
======================================
  Files          17     17            
  Lines        3142   3385   +243     
  Branches      615    767   +152     
======================================
+ Hits         3142   3385   +243

Impacted Files	Coverage Δ
pydantic/version.py	100% <100%> (ø)	⬆️
pydantic/validators.py	100% <100%> (ø)	⬆️
pydantic/fields.py	100% <100%> (ø)	⬆️
pydantic/schema.py	100% <100%> (ø)	⬆️
pydantic/env_settings.py	100% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0c18619...71ab229. Read the comment docs.

[samuelcolvin]

@dmontagu please let me know what you think about this. I ended up supporting TypeVar to fix this.

I guess the documentation needs a new section on this.

[samuelcolvin]

@dmontagu @tiangolo @koxudaxi

This and #969 should go out ASAP as fixes.

Do we want to do a new release from master v1.1 which would include the mypy plugin etc., or base this off the v1 tag and do a v1.0.1 release?

I think we might as well go straight to v1.1 but if anyone has a strong feeling about this, please let me know here.

[dmontagu]

I think the support for TypeVar constraints/bounds is pretty awesome!

I'm in favor of releasing this as 1.1 with the mypy plugin. Considering the full backwards compatibility, I don't think there is a need to make a 1.0.1 release first. But either way is fine with me.

I would release the bug fixes prior to dropping non-plugin support for type-checking the pydantic.dataclasses.dataclass decorator though. I'm not sure how to consider changes to type checking behavior in the context of semver; I don't think it rises to the level of being considered a "breaking change", but presumably releasing a bugfix to the same minor version would be preferable if an update requires changes to get type checking to pass.