Disable threads in uWSGI

Threading in the uWSGI configuration seems to refer to Python threads. By default, threading support is disabled for performance reasons. Quoting from the documentation (https://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html)

By default the Python plugin does not initialize the GIL. This means your app-generated threads will not run. If you need threads, remember to enable them with enable-threads. Running uWSGI in multithreading mode (with the threads options) will automatically enable threading support. This “strange” default behaviour is for performance reasons, no shame in that.

As we do not use Python threads, it would be better to disable threading support.