test(python): Add/fix version-gating in some SQLAlchemy and Pandas tests

[alexander-beedie]

Closes #17487.

Adds/tweaks some version-gating for a couple of tests.

• One test should have been gated on the Pandas version, but was using the Python version to imply this instead.
• Also, there's still a large SQLAlchemy 1.x install base (and it has been updated independently of 2.x as recently as March), so allowing tests to run with both versions is worthwhile (we still run it in a few places at work, for example, due to some otherwise incompatible drivers).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.47%. Comparing base (daf2e49) to head (84ab86f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17538      +/-   ##
==========================================
- Coverage   80.48%   80.47%   -0.01%     
==========================================
  Files        1483     1483              
  Lines      195118   195118              
  Branches     2778     2778              
==========================================
- Hits       157039   157025      -14     
- Misses      37568    37582      +14     
  Partials      511      511              

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