Exercise 3: Invalid path to exercise 0

[bnubald]

Branch: updates-for-rocky9-oct24
Reference:

jasmin-workshop/exercises/ex03/README.md

Line 31 in e3f0c06

* Local machine set up as per [exercise 0](..ex00), with:

There is a forward slash missing in the path to ex00, so, gives invalid path error.

Solution:
Update to ../ex00.