add spark_to_pandas method

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 37.50000% with 5 lines in your changes missing coverage. Please review.

Project coverage is 48.57%. Comparing base (0358038) to head (b73798b).

Files	Patch %	Lines
src/notebook_utils/notebook_utils.py	37.50%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #31 +/- ## ========================================== - Coverage 50.00% 48.57% -1.43% ========================================== Files 4 4 Lines 98 105 +7 ========================================== + Hits 49 51 +2 - Misses 49 54 +5 ```

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