Migrate to Pydantic 2.0 standards

[bachya]

Describe what the PR does:

#176 allowed us to bump pydantic above 2.0.0, but it still utilized <2.0.0 patterns. This PR migrates things to use 2.0.0+ standards.

Does this fix a specific issue?

N/A

Checklist:

• Confirm that one or more new tests are written for the new functionality.
• Run tests and ensure everything passes (with 100% test coverage).
• Update README.md with any new documentation.

[codecov]

Codecov Report

Merging #195 (8cd98aa) into dev (4a58893) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##               dev      #195   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           14        14           
  Lines          505       486   -19     
=========================================
- Hits           505       486   -19     

Files Changed	Coverage Δ
aiopurpleair/helpers/validator/__init__.py	100.00% <ø> (ø)
aiopurpleair/helpers/validator/sensors.py	100.00% <ø> (ø)
aiopurpleair/api.py	100.00% <100.00%> (ø)
aiopurpleair/endpoints/__init__.py	100.00% <100.00%> (ø)
aiopurpleair/helpers/model.py	100.00% <100.00%> (ø)
aiopurpleair/models/keys.py	100.00% <100.00%> (ø)
aiopurpleair/models/sensors.py	100.00% <100.00%> (ø)