get_key_def(): unnecessary logging polutes stderr

[remtav]

https://github.com/NRCan/geo-deep-learning/blob/develop/utils/utils.py#L169

    if not val:  # Skips below if statements if val is None
        logging.error(f"The key {key} as a None value.")

The "val" variable may be None without it being an error. This logging message appears over and over during inference, for example. I'd suggest removing this logging altogether.

@CharlesAuthier this was added in your PR: https://github.com/NRCan/geo-deep-learning/pull/478/files#diff-9653b8c2ce917a6134298b00c8b3f7d4b7c4dc473a752303f37a870392742127R167
any particular use for this error message?