A soft reset of the SCD30 sensor, i.e.
calling SCD30.reset() was added in commit
fe023428 to force an instant update of
the measurement interval after bootup.
It seems, however, that the calibration value is not stored if the sensor is reset before carrying out at least one measurement after calibration. This breaks calibration with the current code, because the ESP (and then the SCD30) is reset directly after calibration.