FIX: remove deprecated pandas CSV reader args (keep_date_col, verbose, delim_whitespace)

[iprithv]

fix: remove deprecated pandas CSV reader args (keep_date_col, verbose, delim_whitespace) fixes #1417

These pandas arguments are deprecated and generate warnings during the test suite.
This PR removes them from Hamilton’s PandasCSVReader to maintain future compatibility and keep test output clean.

Changes

• Removed usage of deprecated pandas CSV parameters:
  • keep_date_col
  • verbose
  • delim_whitespace
• Updated _get_loading_kwargs() to avoid passing these keywords.
• Ensures compatibility with newer pandas versions (≥ 2.x).
• Eliminates deprecation warnings observed.

How I tested this

• Ran the test suite with pytest
• Confirmed that CSV-related tests pass without warnings

Notes

Checklist

• [x] PR has an informative, human-readable title
• [x] Changes limited to a single goal
• [x] Code passes pre-commit and removes old warnings
• [x] No functional behaviour change; only param cleanup
• [x] Any updated helper logic covered by existing tests
• [x] No leftover TODOs or placeholder code
• [x] Documentation not required (internal cleanup)