Stretch Goal: Friend group data functions

[dpshelio]

Now that you've got a structure for your group in #5, we'd like you to create a new branch off your current group branch and create some functions.

Every group

1. Create a new branch from your current group branch that starts with stretch_. e.g. stretch_dpshelio-arcteaching-willgraham01
2. Discuss with your group the best way to make the following functions, you can add extra parameters to the functions if you think it would be useful.
   1. forget(person1, person2) which removes the connection between two people in the group
   2. add_person(name, age, job, relations) which adds a new person with the given characteristics to the group
   3. average_age() which calculates the mean age for the group
3. Commit your changes to your branch! (with a meaningful message)
4. Push your changes from your computer to your fork.
5. Create a pull request (PR) from your branch to original friend-group repository.
   Add a meaningful title to that PR and don't forget to mention your partners in the description (as @username) and a link to this issue: Answers UCL-COMP0233-24-25/RSE-Classwork#6