fix shapes

Author: haraschax

rednose/helpers/kalmanfilter.py

@@ -5,8 +5,8 @@
 
 class KalmanFilter:
   name = "<name>"
-  initial_x = np.zeros((0, 0))
-  initial_P_diag = np.zeros((0, 0))
+  initial_x = np.zeros((0,))
+  initial_P_diag = np.zeros((0,))
   Q = np.zeros((0, 0))
   obs_noise: dict[int, Any] = {}