update to timings

[colinsauze]

Some episodes are missing timings for exercises. Here is the data from the December 2024 teaching of this lesson:

day 1

python started 14:00
finished 17:00, reached exercises at end of visualisation

day 2

started 9:30
9:30-10:00 completed visualisation

10:00 - 10:?? lists

10:?? - 11:00 loops

loops exercise started 10:45

break 11:00-11:20

looping over files teaching 11:20 - 11:50
exercise 11:50 - 11:55

conditionals 11:55 - 12:35

functions 12:35 - 13:00