Fix bug caused by matplotlib API change

Closes #283 (closed)

Matplotlib 3.9.0 changes the API of Line2D such that it does not accept non-sequence data anymore. This breaks the code for setting the zoom marker and time marker in the TPS plot.

Reference: https://matplotlib.org/stable/api/prev_api_changes/api_changes_3.9.0.html#line2d (technically, the broken code uses Line2D.set_data(), but that method itself uses Line2D.set_xdata(), whose API was changed)