TCRM 3.1.9
Minor bugfix update:
track.ncReadTrackData previously returned cftime.DatetimeGregorian objects, which caused newer versions of matplotlib.dates.num2date to fail. This is because we write the tracks with units of 'hours since 1900-01-01 00:00', but matplotlib.dates uses 1970-01-01 as the epoch, and works in units of days (with no way to specify units in the num2date function). This update ensures datetime objects returned by ncReadTrackData are true python datetime objects
Also changing to Github actions for continuous integration testing