Rewrite fibonacci.py (#5665) (#5677)

* Removed doctest call

* Removed 0 and 1 append to `fib_array`

* Moved fibonacci sequence logic into `calculate`

* Refactored `get` to generate missing numbers

* Renamed `fib_array` to `sequence`

* Renamed `number` to `index`

* Refactored `get` to only return sequence to `index`

* Moved main block into function

* Added documentation to `get`

* Added missing type hints

* Fixed doctest error in `get` docstring

* Moved calculate logic into get

* Reformatted with black

* Fixed wrong generation range