Error handling for invalid date (and potentially other errors)

[ecatkins]

It appears if you reach the historical limit for weather data (e.g. I was trying to scrape for a date in 2008), the API returns an error message:

{'error': [{'msg': 'There is no weather data available for the date provided.'}]}

However the library currently does not handle for this, and just errors with:

  File "/my/path/lib/python3.8/site-packages/wwo_hist/__init__.py", line 103, in retrieve_this_location
    data = json_data['data']['weather']
KeyError: 'weather'

Would it be desirable to at least provide this error message back to the user? I'm happy to make a pull request if you agree