Upgrade pydantic version and update corresponding fsapi code

[MichaelPesce]

Fixes/Resolves:

#1273

Summary/Motivation:

Other packages are reliant on pydantic having version >= 2.0.0

Changes proposed in this PR:

• remove the requirement that watertap package has pydantic < 2
• add requirement that watertap has pydantic >= 2
• migrate pydantic code to use v2 syntax

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov]

Codecov Report

Attention: Patch coverage is 97.87234% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 94.25%. Comparing base (1849b8a) to head (a2c2f85).

Files	Patch %	Lines
watertap/ui/fsapi.py	97.87%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1330      +/-   ##
==========================================
- Coverage   94.25%   94.25%   -0.01%     
==========================================
  Files         370      370              
  Lines       37952    37951       -1     
==========================================
- Hits        35770    35769       -1     
  Misses       2182     2182              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[lbianchi-lbl]

Thanks for taking care of this @MichaelPesce!