Incorrect encoding when saving file with special characters

[Former user]

By defining the filename with a special character (for example, the letter ä, ö, ü) the specials characters were saved as �

string fileName;

...

new AssimpContext().ExportFile(Scene, fileName, "glb2");

For example, if the fileName is "gebäude und gerüst.glb", tt will be saved as "geb�ude und ger�st.glb"