Pyaxiom

Release for a single bugfix (extracting attributes to JSON that were not strings was always `None`)

Bugfix release

- Added CF DGS classes

There were no `1.1.14` and `1.1.15` releases. PyPI wasn't working when I went to upload them.
- Don't try to create a sensor_depth variable if no verticals exist
- Fix long-standing bug causing an EnhancedDataset to never be closed. Thanks RSully.
- Avoid int32 overflows when dealing with large time values

- TimeSeries - Additional UDDC compatibility
- TimeSeries - Add a create_instrumnet_variable argument to add_variable. Defaults to false for backwards compatiblity.
- TimeSeries - Add global attribute 'platform'.
- TimeSeries - Adds URN as the platform ioos_code and long_name attribute if the passed in station_name is a URN.

- Don't ever use int64 (because DAP)