Upgrade to Pydantic 2

[callumforrester]

Fixes #273

Supersedes #449

Currently scanspec is spoofed, we need bluesky/scanspec#122 merged before we can revert.

[codecov]

Codecov Report

Attention: Patch coverage is 96.96970% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.97%. Comparing base (fd41e57) to head (ba38a8a).
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/blueapi/core/context.py	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #564      +/-   ##
==========================================
+ Coverage   92.84%   92.97%   +0.12%     
==========================================
  Files          40       40              
  Lines        1818     1823       +5     
==========================================
+ Hits         1688     1695       +7     
+ Misses        130      128       -2     

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