min_dt_ptp not activated in TimeSeries mode

[friedrichknuth]

dt_stack_ptp must be pre-computed and provided here in order for the temporal.ma_linreg function to apply the min_dt_ptp filter here.

PR #67 implements a similar timedelta filter that will return np.nan if the delta is greater than n days. This can be activated here.

Once implemented for the TimeSeries mode, these results can be compared for validation purposes, assuming there are instances where the condition applies.