Update keepassx_de.ts

improvable version of translationfile (english -> german)
The relevant source code is here: https://github.com/keepassx/keepassx/blob/2190260a687f88855d8a6f4d01dbf832ccf19312/src/core/PasswordGenerator.cpp#L110 (flag 'ExcludeLookAlike')

You are right, they don't compare '1' and 'l'. They simply don't allow these characters.