Deselecting all keyframes with Python My situation right now:
I am able to deselect all objects with Python by doing bpy.ops.object.select_all(action='DESELECT').

My goal: Deselect all Keyframes of the active object with Python.
Deselect all keyframe points and handles

Helper method to deselect all fcurves and their keyframes and handles of an objects action.

import bpy


def deselect_all_keyframes(ob):
    ob.animation_data_create()
    action = ob.animation_data.action

    if action:
        # deselect all fcurves
        action.fcurves.foreach_set)
                "select",
                (False,) * len(action.fcurves),
                )
        # deselect all keyframes
        for fc in action.fcurves:
            for select in ("select_control_point",
                           "select_left_handle",
                           "select_right_handle",
                               ):
                fc.keyframe_points.foreach_set(
                        select, 
                        [False] * len(fc.keyframe_points)
                        )

# test call on context object                        
deselect_all_keyframes(bpy.context.object)