[Linux] Crash when using special characters like ü,ö,ä as custom Tonie name

[AlbrechtL]

Teddy crashes when using special characters like ü,ö,ä as custom Tonie name.

Observed under Ubuntu 20.04 using https://github.com/AlbrechtL/teddy/releases/tag/v1.2.4-linux

System.ExecutionEngineException: String conversion error: Illegal byte sequence encounted in the input.
  at (wrapper managed-to-native) System.Runtime.InteropServices.Marshal.PtrToStringAnsi(intptr)
  at System.Windows.Forms.XplatUIX11.TranslatePropertyToClipboard (System.IntPtr property) [0x0005f] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.XplatUIX11.UpdateMessageQueue (System.Windows.Forms.XEventQueue queue, System.Boolean allowIdle) [0x00918] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.XplatUIX11.ClipboardRetrieve (System.IntPtr handle, System.Int32 type, System.Windows.Forms.XplatUI+ClipboardToObject converter) [0x0002f] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.XplatUI.ClipboardRetrieve (System.IntPtr handle, System.Int32 type, System.Windows.Forms.XplatUI+ClipboardToObject converter) [0x00000] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.Clipboard.GetDataObject (System.Boolean primary_selection) [0x00039] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.Clipboard.GetDataObject () [0x00000] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.TextBoxBase.ProcessKey (System.Windows.Forms.Keys keyData) [0x000a4] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.TextBoxBase.WndProc (System.Windows.Forms.Message& m) [0x0005b] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.TextBox.WndProc (System.Windows.Forms.Message& m) [0x0011c] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.Control+ControlWindowTarget.OnMessage (System.Windows.Forms.Message& m) [0x00000] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.Control+ControlNativeWindow.WndProc (System.Windows.Forms.Message& m) [0x0000b] in <a0f8b82443494dec9b517126f4032efe>:0 
  at System.Windows.Forms.NativeWindow.WndProc (System.IntPtr hWnd, System.Windows.Forms.Msg msg, System.IntPtr wParam, System.IntPtr lParam) [0x00085] in <a0f8b82443494dec9b517126f4032efe>:0