Prevent rotation of the bevel object (Should stay parallel to the XY plane)

Question

How to prevent bevel shape rotation in extrusion operations?

I would like the final shape to remain "parallel" to the XY plane.

At the end of the extrusion (Due to the change of Z along the path) my profile shape has rotated:

Here is my code

def create_rectangular_curve(objname, lenX, lenY):
    # create the Curve and the spline
    ratioY=lenY/lenX
    mycurve = bpy.data.curves.new(objname, type='CURVE')
    mycurve.dimensions = '2D'
    spline = mycurve.splines.new(type='POLY')
    #add points to the spline
    spline.points.add(4)
    spline.points[0].co=(-lenX/2,-lenY/2,0,1)
    spline.points[1].co=(lenX/2,-lenY/2,0,1)
    spline.points[2].co=(lenX/2,lenY/2,0,1)
    spline.points[3].co=(-lenX/2,lenY/2,0,1)
    spline.points[4].co=(-lenX/2,-lenY/2,0,1)    
    #create Object
    myobject = bpy.data.objects.new(objname, mycurve)
    bpy.context.scene.collection.objects.link(myobject)
    return myobject
def create_saw_curve(objname, nbPeriode, sizeX, sizeY):
    # create the curve and the spline
    ratioY=sizeY/sizeX
    mycurve = bpy.data.curves.new(objname, type='CURVE')
    mycurve.dimensions = '3D'
    spline = mycurve.splines.new(type='BEZIER')
    #add points to the spline
    spline.bezier_points.add(nbPeriode4)
    #the first one
    spline.bezier_points[0].co=(0,0,-1)
    spline.bezier_points[0].handle_left =(-1,-ratioY,-1)
    spline.bezier_points[0].handle_right =(1,ratioY,-1)
    #the others points
    for i in range(1, nbPeriode4,4):
        spline.bezier_points[i].co=(isizeX,sizeY,0)
        spline.bezier_points[i].handle_left =(isizeX-1,sizeY-ratioY,0)
        spline.bezier_points[i].handle_right =(isizeX+1,sizeY-ratioY,0)
        spline.bezier_points[i+1].co=((i+1)sizeX,0,1)
        spline.bezier_points[i+1].handle_left =((i+1)sizeX-1,ratioY,1)
        spline.bezier_points[i+1].handle_right =((i+1)sizeX+1,-ratioY,1)
        spline.bezier_points[i+2].co=((i+2)sizeX,-sizeY,0)
        spline.bezier_points[i+2].handle_left =((i+2)sizeX-1,-sizeY+ratioY,0)
        spline.bezier_points[i+2].handle_right =((i+2)sizeX+1,-sizeY+ratioY,0)
        spline.bezier_points[i+3].co=((i+3)sizeX,0,-1)
        spline.bezier_points[i+3].handle_left =((i+3)sizeX-1,-ratioY,-1)
        spline.bezier_points[i+3].handle_right =((i+3)sizeX+1,ratioY,-1)
    #create Object
    myobject = bpy.data.objects.new(objname, mycurve)
    bpy.context.scene.collection.objects.link(myobject)
    return myobject
profileObject = create_rectangular_curve("profil", 4, 2)
curveObject = create_saw_curve('saw_curve',2,10,20)
curveObject.data.bevel_object = profileObject
curveObject.data.use_fill_caps = True 
curveObject.data.bevel_mode = 'OBJECT'