fix: make precip_nowcast four dimensional

[RubenImhoff]

Fixes #529

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.83%. Comparing base (fa1c5d2) to head (fa9d6ca).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #530   +/-   ##
=======================================
  Coverage   83.83%   83.83%           
=======================================
  Files         168      168           
  Lines       14621    14621           
=======================================
  Hits        12258    12258           
  Misses       2363     2363           

Flag	Coverage Δ
unit_tests	83.83% <ø> (ø)

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[dnerini]

great, thanks, now the example compiles without errors!