Speed up data preprocessing save_to_disk

[boat1603]

Why this PR

This PR is about using num_proc arguments on save_to_disk function to speed up saving dataset.

Changes

• Add num_proc arguments on save_to_disk function

Related Issues

Close #

Checklist

• [ ] PR should be in the Naming convention
• [ ] Assign yourself in to Assigneees
• [ ] Tag related issues
• [ ] Constants name should be ALL_CAPITAL, function name should be snake_case, and class name should be CamelCase
• [ ] complex function/algorithm should have Docstring
• [ ] 1 PR should not have more than 200 lines changes (Exception for test files). If more than that please open multiple PRs
• [ ] At least PR reviewer must come from the task's team (model, eval, data)

[codecov[bot]]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (361a98f) 19.39% compared to head (a085f01) 19.39%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #315 +/- ## ======================================= Coverage 19.39% 19.39% ======================================= Files 25 25 Lines 1392 1392 ======================================= Hits 270 270 Misses 1122 1122 ``` | [Flag](https://app.codecov.io/gh/OpenThaiGPT/openthaigpt-pretraining/pull/315/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OpenThaiGPT) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/OpenThaiGPT/openthaigpt-pretraining/pull/315/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OpenThaiGPT) | `19.39% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OpenThaiGPT#carryforward-flags-in-the-pull-request-comment) to find out more.

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