fix: add missing 'Sabah' to supported region list

[utrodus]

Hi Hafiq Iqmal 👋🏻

This pull request fixes Fatal error when filtering by state Sabah: Class "HttpException" not found, where the state Sabah was missing from the list of supported regions in the MalaysiaHoliday class.

🛠️ Changes made:

• Added 'Sabah' to the self::$region_array in MalaysiaHoliday.php.

🐛 Root Cause:

The checkRegional() method validates the requested region against the self::$region_array. Since 'Sabah' was not listed, any request involving 'Sabah' resulted in a RegionException, causing the script to fail when attempting to fetch holidays for that region.

✅ Testing:

I verified the fix by running the following code:

$holiday = new MalaysiaHoliday();
$data = $holiday->fromState('Sabah', 2025)->get();

This now successfully returns holiday data for Sabah in 2025 without throwing an exception.

Closes #12

[utrodus]

I noticed that the GitHub Actions build is currently failing on my pull request due to the following error:

Error: Missing download info for actions/cache@v2

Here’s the failed build:
🔗 GitHub Actions Job

This seems to be related to an outdated version of the actions/cache GitHub Action. The v2 version might have been deprecated or moved. You can find the updated version here on the GitHub Marketplace:
📦 [actions/cache on GitHub Marketplace](https://github.com/marketplace/actions/cache)

You might want to update the version to actions/cache@v3 in the workflow file to resolve this issue.

Let me know if you'd like me to help create a quick PR to fix it 🙌🏻