Allow Cell.value to be float

[robertmetcalf]

In file cell/cell.pyi, the Cell() class defines

• value: Optional[Union[datetime.date, str, int]] = ...,

Consider adding float as a type.

• value: Optional[Union[datetime.date, str, int, float]] = ...,

See the documentation for openpyxl.cell.cell module.

[MartinThoma]

If you add a pr, I'll accept it :-)