Rewrite *other* fibonacci.py #5733
Description
I opened issue #5665 to have fibonacci.py rewritten, but apparently there are multiple files with that name. The PR that @citharus made (#5677) revamps the file dynamic_programming/fibonacci.py (thanks for your contributions btw!) whereas this issue seeks to revamp the file maths/fibonacci.py.
I'm opening this as a new issue since it's technically a different algorithm file and the two fibonacci.py files each use different algorithms to calculate the Fibonacci sequence.