polars support for `xlsx_table`

[samukweku]

PR Description

Please describe the changes proposed in the pull request:

• xlsx_table now supports polars

jn.xlsx_table('../Downloads/016-MSPTDA-Excel.xlsx', table='dCategory',engine='polars')
Out[31]: 
shape: (5, 2)
┌────────────┬───────────────┐
│ CategoryID ┆ Category      │
│ ---        ┆ ---           │
│ i64        ┆ str           │
╞════════════╪═══════════════╡
│ 1          ┆ Beginner      │
│ 2          ┆ Advanced      │
│ 3          ┆ Freestyle     │
│ 4          ┆ Competition   │
│ 5          ┆ Long Distance │
└────────────┴───────────────┘

This PR relates to #1352

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Relevant Reviewers

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• @ericmjl

[ericmjl]

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