Determine if the given depth is contained within a fluid zone.

The fluid zone includes its upper boundary but not its lower boundary. The top and bottom of the fluid zone are not returned as a DepthRange, just like in the Java code, despite its claims to the contrary.

Parameters:depth (ndarray, dtype = float) The depth to check, in km.
Returns:True if the depth is within a fluid zone, False otherwise.
Return type:ndarray (dtype = bool)