[#42733] Fixes menu verification check for menu types with Unicode characters

[Kubik-Rubik]

Pull Request for Issue #42733.

Summary of Changes

This small change fixes the menu verification check for menu types with Unicode characters, such as German umlauts (ä, ü, ö).

Testing Instructions

1. Enable the option "Unicode Aliases" in the global settings
2. Create a new menu with the name "Menü" and the unique name "menü"
3. Open the "All Menu Items" page and select the newly created menu from the drop-down list

Actual result BEFORE applying this Pull Request

You will see the error "The Menu type doesn't exist." and all menu items are loaded.

Expected result AFTER applying this Pull Request

No error is displayed, and the correct menu items are loaded.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:
• No documentation changes for docs.joomla.org needed
• Pull Request link for manual.joomla.org:
• No documentation changes for manual.joomla.org needed

[fgsw]

I have tested this item ✅ successfully on a8ee968

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[Quy]

I have tested this item ✅ successfully on a8ee968

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42741.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42741.}

[MacJoom]

Thank you!