[v2.2.0] - 2023.04.18

Added

• Ability to constrain the max price of retrieved flights/trips from the API when
  using get_cheapest_flights or get_cheapest_return_flights via the max_price kwarg.
• Added currency field to the Flight object.
  • Availability API method get_all_flights does not support specifying currency (it is always the currency of the
    departure country), but this was not documented. Flight will now allow the user to see what currency has been
    returned.
• Log a warning when returned currency doesn't match the configured value.
  • Primarily to warn users using the get_all_flights API that the response isn't as configured.
  • Might also be useful if the get_cheapest_flights and get_cheapest_return_flights APIs ever stop respecting
    requests for results in specific currencies.

Fixed

• Incorrect date format used for logs.

Changed

• It is now optional to specify currency when creating an instance of the library.
  • If not specified, the API decides the return currency (normally the currency of the departure country).
  • If an API, such as the availability / get_all_flights API, doesn't support it anyway, this will be ignored,
    except for the purposes of deciding whether a warning should be shown, where the currencies mismatch.