BB84 QKD algorithm (#7898)

* Added BB84 algorithm.

* Function name lowercase + imports fix

I thought uppercase was appropriate because they're initials.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update quantum/bb84.py

Co-authored-by: Christian Clauss <[email protected]>

* Removed python < 3.11 restriction from qiskit

* Removed python < 3.11 restriction from qiskit

* scikit-learn

* Update quantum/bb84.py

Correct typo in `default_rng()` call

Co-authored-by: Maxim Smolskiy <[email protected]>

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <[email protected]>
Co-authored-by: Maxim Smolskiy <[email protected]>