Exception with address line

[ehibes]

Hi,

I noticed a problem creating payment form. If I put this address 2 avenue de la botte aux bailles, Bâtiment Pasaïa I get an exception for invalid address.

String	Status	Length(mb_strlen)
2 avenue de la botte aux bailles, Bâtiment Pasaïa	KO ❌	49
2 avenue de la botte aux bailles, Bâtiment Pasaï	OK ✅	48
2 avenue de la botte aux bailles, Bâtiment Pasaia	OK ✅	49
Bâtiment Pasaïa	OK ✅	15

The problem is string assert function that use strlen instead of mb_strlen
I made a PR with test & update.