TeamSpeak on Ubuntu: Fix InitializeSandbox() called with multiple threads in process gpu-process

I got the following problem after upgrading to Ubuntu 20.04:

terminating
[0100/000000.565331:ERROR:sandbox_linux.cc(374)] InitializeSandbox() called with multiple threads in process gpu-process.
Aborted (core dumped)

@ibk in the TeamSpeak community found something like a fix for it:

mkdir -p $HOME/.config/TeamSpeak/Default

https://community.teamspeak.com/t/teamspeak-client-does-not-start-on-linux-solved-but-not-fixed/13112/42 (Source)