Fix: Restore dev branch regression with Ticker.history()

[dhruvan2006]

Fix regression introduced by #2192 that broke the functionality of the dev branch while implementing custom periods.

Ticker.history() and download() methods were broken.

[ValueRaider]

Can you give an example regression scenario?

[dhruvan2006]

On dev branch:

import yfinance as yf

hist = yf.Ticker("AAPL").history()
print(hist)

Traceback (most recent call last):
File "C:\Users\dhruv\yfinance\test.py", line 3, in
hist = yf.Ticker("AAPL").history()
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\dhruv\yfinance\yfinance\utils.py", line 103, in wrapper
result = func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\dhruv\yfinance\yfinance\base.py", line 81, in history
return self._lazy_load_price_history().history(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\dhruv\yfinance\yfinance\utils.py", line 103, in wrapper
result = func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\dhruv\yfinance\yfinance\scrapers\history.py", line 109, in history
end = utils._parse_user_dt(end, self.tz)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\dhruv\yfinance\yfinance\utils.py", line 427, in _parse_user_dt
dt = int(dt.timestamp())
^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'timestamp'

[ValueRaider]

Thanks.

@R5dan FYI your PR #2192 was broken, and didn't handle custom period strings.

[R5dan]

Sorry, should have done more testing. Probably happened when moving functionality from Ticker.history to utils.