Old matplotlib animation now fails

Some years ago I created a Python program that reads GPS data and
creates an animation stored in an mp4 file. Not very elegant but it
worked. Not very original as it was based on the example found here:

https://shorturl.at/dTCZZ

Last time it worked was about a year ago. Since then I have moved to a
later version of Debian and Conda and as a consequence a later version
of Python 3 (now 3.12.2).

Now my code fails. I have downloaded the latest version of the example
and it also fails.

It is the second to last line that throws an error:

l.set_data(x0, y0)

The error messages drills down to something called
"/home/.../matplotlib/lines.py", line 1289, in set_xdata

and tells me 'x must be a sequence'

I have started to dig around in matplotlib's documentation but my
strategy is clearly wanting. I don't really know where to start
looking for information on how to correct my code. Hence, this
call for help.

Any ideas?

TIA

/Martin