Forcing the backend to TkAgg prevents to run lucid3 without a X server (like in a docker container). A display is only needed when using --display.
Let matplotlib detect the proper backend to use.

From https://matplotlib.org/stable/users/explain/backends.html:

Without a backend explicitly set, Matplotlib automatically detects a usable backend based on what is available on your system and on whether a GUI event loop is already running. The first usable backend in the following list is selected: MacOSX, QtAgg, GTK4Agg, Gtk3Agg, TkAgg, WxAgg, Agg. The last, Agg, is a non-interactive backend that can only write to files. It is used on Linux, if Matplotlib cannot connect to either an X display or a Wayland display.

Using use will require changes in your code if users want to use a different backend. Therefore, you should avoid explicitly calling use unless absolutely necessary.