chore: replace snapshottest with syrupy and support py3.12

[GG-HH]

Context

An attempt to fix #832 and bring python3.12 support.

What has been done

1. Replace snapshottest with syrupy
2. Add py3.12 in the test matrix

Validation

Run tests with a python3.12 environment
Ensure there is nowhere where I should update to python3.12 that was forgotten

PR check list

• As much as possible, the changes include tests (unit and/or functional)
• If the changes affect the end user (new feature, behavior change, bug fix) then the PR has a changelog entry (see doc/dev/getting-started.md). If the changes do not affect the end user, then the skip-changelog label has been added to the PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.99%. Comparing base (c3d4753) to head (9d2d829).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1118   +/-   ##
=======================================
  Coverage   91.99%   91.99%           
=======================================
  Files         144      144           
  Lines        6162     6162           
=======================================
  Hits         5669     5669           
  Misses        493      493           

Flag	Coverage Δ
unittests	91.99% <ø> (ø)

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