IoT-data-visualization.py: socketio import failures

[YannGarcia]

Describe the bug
Some modules import seem to incorrect with Python3 current socketio module:

vagrant@ubuntu1804:~/tmp/OpenMTC/doc/example-apps$ ./start-simple-app
[1] IoT-data-visualization.py
[2] simple-decision-2.py
[3] simple-decision.py
[4] data-aggregation.py
Choose the app to start: 1

PYTHONPATH: :/home/vagrant/tmp/OpenMTC/doc/../futile/src:/home/vagrant/tmp/OpenMTC/doc/../common/openmtc/lib:/home/vagrant/tmp/OpenMTC/doc/../common/openmtc-onem2m/src:/home/vagrant/tmp/OpenMTC/doc/../common/openmtc/src:/home/vagrant/tmp/OpenMTC/doc/../serializers/*/src:/home/vagrant/tmp/OpenMTC/doc/../openmtc-app/src
Traceback (most recent call last):
File "/home/vagrant/tmp/OpenMTC/doc/example-apps/IoT-data-visualization.py", line 5, in
from openmtc_app.onem2m import XAE
File "/home/vagrant/tmp/OpenMTC/openmtc-app/src/openmtc_app/onem2m.py", line 27, in
from openmtc_app.flask_runner import FlaskRunner
File "/home/vagrant/tmp/OpenMTC/openmtc-app/src/openmtc_app/flask_runner/init.py", line 8, in
from socketio import Server as SioServer, Middleware as SioMiddleware
ImportError: cannot import name 'Server'

Desktop (please complete the following information):
Linux ubuntu1804.localdomain 4.15.0-72-generic #81-Ubuntu SMP Tue Nov 26 12:20:02 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Python 3.6.9