docs: update import statement in the `GT.data_color()` example

[jrycw]

I propose changing the import statement in the GT.data_color() example to follow a more commonly used pattern.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.37%. Comparing base (11660a6) to head (df6f377). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #432 +/- ## ======================================= Coverage 86.37% 86.37% ======================================= Files 42 42 Lines 4683 4683 ======================================= Hits 4045 4045 Misses 638 638 ```

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