Spices Settings filechooser not working when choosing directory with special characters (non ASCII characters?)

[jonath92]

The settings file chooser is not working when not choosing a directory with some special characters (non ASCII characters?) such as 'ä' or 'ö'

Cinnamon version : 5.0.7
Distribution: Mint 20.2
64 bit

Issue
When selecting a directory with non ASCII characters in a filechooser, it is saved some weird string in the settings [uuid].json file

Steps to reproduce

1. Install the radio applet (it is not the fault of the applet. I am the maintainer and have checked that)
2. create a folder with non UTF-8 characters, e.g: такого or 'töst
3. open the radio applet settings, go to the "Preferences" Tab and select as "Download directory" the folder created in step 2
4. open the radio settings file: ~/.cinnamon/configs/radio@driglu4it
5. view the value of the music-download-dir widget. It looks somehow like: file:///home/jonathan/Tmp/%D1%82%D0%B0%D0%BA%D0%BE%D0%B3%D0%BE

Expected behaviour
The correct path is shown

Other information
I have added some print statements in my /usr/share/cinnamon/cinnamon-settings/bin/JsonSettingsWidgets.py and it is there already false. This is why I am sure that it is not something wrong in the applet code