swi_calc_cy_noise doesn't handle nans

[Adeaem]

calc_swi_ts() takes a nan parameter and passes it to the underlying swi_calc_cy() function
https://github.com/TUW-GEO/pyswi/blob/independent_swi_calc/src/pyswi/swi_ts/swi_ts.py#L212

but in presence of 'sm_noise' field, the nan is not passed to swi_calc_cy_noise() and just treats the nan value as soil moisture
https://github.com/TUW-GEO/pyswi/blob/independent_swi_calc/src/pyswi/swi_ts/swi_ts.py#L206