receive_time: fix week day

[lcmcninch]

Fixes #137

• Describe scope of change. Implements a method to parse the dict returned by the server and correct the week day. Only the receive_time method is affected

• Describe any known limitations with your change. N/A

• Please run any tests or examples that can exercise your modified code. Updated test_time_data to verify week day and added a test for the new method that tests every day of the week.

[brentru]

Merging as https://github.com/adafruit/Adafruit_IO_Python/commit/6587c92bb6fd124c36f9fabe66a2325aeea8dd97 will catch future requests failing with external forks, via https://dev.to/petrsvihlik/using-environment-protection-rules-to-secure-secrets-when-building-external-forks-with-pullrequesttarget-hci