refactor: add the `u` flag in regular expressions

[deepsource-autofix[bot]]

It is recommended to use the u flag with regular expressions.

[deepsource-io[bot]]

Here's the code health analysis summary for commits 642003c..ea01593. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
PHP	✅ Success		View Check ↗
JavaScript	✅ Success	🎯 1 occurence resolved	View Check ↗

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