`upcase` expression with Greek lowercase letters with accents does not remove accents

[wipfli]

maplibre-gl-js version: 4.5.0

browser: chrome

Steps to Trigger Behavior

1. Have a property with a lowercase greek string that has accents
2. Turn it to uppercase with the upcase expression
3. See how accent are not removed

Link to Demonstration

https://jsbin.com/jukebec/edit?html,output

Expected Behavior

with name = Μυρτώο Πέλαγος
['upcase', ['get', 'name']] gives ΜΥΡΤΩΟ ΠΕΛΑΓΟΣ

Actual Behavior

with name = Μυρτώο Πέλαγος
['upcase', ['get', 'name']] gives ΜΥΡΤΏΟ ΠΈΛΑΓΟΣ