install: update minimal Brython version to 3.9.2 to have fixed elements's `children` implementation: Before 3.9.2, Brython had an implementation of `children` hidding the DOM method, and which was returning all elements (like childNodes). 3.9.2 fixes it.

"""manage common dialogs"""

from browser import document

def remove_loading_screen():
    print("removing loading screen")
    document['loading_screen'].remove()