WRQ-19156: Update .travis.yml to apply the latest node version

[hong6316]

Checklist

• [x] I have read and understand the contribution guide
• [ ] A CHANGELOG entry is included
• [ ] At least one test case is included for this feature or bug fix
• [x] Documentation was added or is not needed
• [ ] This is an API breaking change

Issue Resolved / Feature Added

In https://github.com/enactjs/enact/pull/3231, We changed node version in .travis.yml to 21 to avoid node 22 error temporarily. We need to revert it to the latest version.

Resolution

Reverted the node version to the latest.

Additional Considerations

Links

WRQ-19156

Comments

Enact-DCO-1.0-Signed-off-by: Taeyoung Hong (taeyoung.hong@lge.com)

[codecov[bot]]

Codecov Report

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

Project coverage is 82.25%. Comparing base (ee038a9) to head (c5d4e2a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #3251 +/- ## ======================================== Coverage 82.25% 82.25% ======================================== Files 152 152 Lines 7084 7084 Branches 1864 1864 ======================================== Hits 5827 5827 Misses 986 986 Partials 271 271 ```

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