pin pydantic < 2

[d-chambers]

Description

Pydantic V2 was released yesterday. It has several breaking changes (which break DASCore) so I am pinning the requirement to less than 2 until we update DASCore's pydantic models.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes.
• documented the new feature with docstrings or appropriate doc page.
• included a test. See testing guidelines.
• your name has been added to the contributors page (docs/contributors.md).
• added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov]

Codecov Report

Merging #181 (3a9ca4f) into master (af75507) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #181   +/-   ##
=======================================
  Coverage   96.77%   96.77%           
=======================================
  Files          58       58           
  Lines        3627     3627           
=======================================
  Hits         3510     3510           
  Misses        117      117           

Flag	Coverage Δ
unittests	96.77% <ø> (ø)

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