Revert "add sourcery.ai github action"
    
    This reverts commit e3f991948a439bd6d84f22263c98a13f9b47d2a0.
    
    Sourcery works right now without adding an action as a webhook, so we
    don't need an action that cannot access secrets when triggered from a
    pull request.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>