Add segfaulting doctest to quantum/bb84.py for demo purposes

[tianyizheng02]

Describe your change:

Per discussion in #8818, I'm making a PR with a doctest for an input size of 100 in quantum/bb84.py to see if it will segfault in GitHub actions.

Update: it does

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[tianyizheng02]

Fatal Python error: /home/runner/work/_temp/f21d497d-6cae-49bd-acfd-3dc4c87d955b.sh: line 1:  1859 Segmentation fault      (core dumped) pytest --ignore=quantum/q_fourier_transform.py --ignore=project_euler/ --ignore=scripts/validate_solutions.py --cov-report=term-missing:skip-covered --cov=. .
quantum/bb84.py 
Error: Process completed with exit code 139.

As expected, running the bb84 function with an input size of 100 causes Python to segfault.

[tianyizheng02]

Closing since this isn't meant to be merged and I've already proven my point