ekf rng kin: reduce minimum rng variance

src/modules/ekf2/EKF/ekf_helper.cpp

@@ -1365,7 +1365,7 @@ float Ekf::getRngHeightVariance() const
 {
 	const float dist_dependant_var = sq(_params.range_noise_scaler * _range_sensor.getDistBottom());
 	const float var = sq(_params.range_noise) + dist_dependant_var;
-	const float var_sat = fmaxf(var, 0.01f);
+	const float var_sat = fmaxf(var, 0.001f);
 	return var_sat;
 }