Scripts: update ota.py

[mcspr]

• follow up for Scripts: memanalyser fixes #2014 , drop py2, try to follow pylint advice (not everything yet), restructure script into functions, fix argparse
• follow up for Python cleanup #1526, use threading helpers and zeroconf discovery through class object
• change default behaviour to print immediately when device is discovered, make --sort optional
• slightly increase timeout and add --timeout NUM

[mcspr]

Note about the 7bf7aa6 merge change. Using // to avoid nesting ints

per https://docs.python.org/3.8/tutorial/introduction.html#numbers:

Division (/) always returns a float. To do floor division and get an integer result (discarding any fractional result) you can use the // operator; to calculate the remainder you can use %