Fix unit tests

[ChristopheVeber]

1. On my end the unit tests are not executable because some arguments are missing:

>       points, start_time, device_name = BuildGPSPoints(data, skip=args.skip, skipDop=args.skip_dop, dopLimit=args.dop_limit)
E       AttributeError: 'Args' object has no attribute 'skip_dop'

In principle this can be fixed by adding something like

args.skip_dop = True
args.dop_limit = 2000

to test_samples.py. => What are the expected parameter values?
2. If I add the above change then asserts fail:

>           assert(s0 == s1)
E           assert '<?xml versio...rk>\n</gpx>\n' == '<?xml versio...n\n</gpx>\n\n'
E
E               <?xml version="1.0" encoding="UTF-8"?>
E             -
E               <gpx xmlns="http://www.topografix.com/GPX/1/1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:wptx1="http://www.garmin.com/xmlschemas/WaypointExtension/v1" xmlns:gpxtrx="http://www.garmin.com/xmlschemas/GpxExtensions/v3" xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v2" xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3" xmlns:trp="http://www.garmin.com/xmlschemas/TripExtensions/v1" xmlns:adv="http://www.garmin.com/xmlschemas/AdventuresExtensions/v1" xmlns:prs="http://www.garmin.com...
E
E             ...Full output truncated (10151 lines hidden), use '-vv' to show

test\test_samples.py:59: AssertionError

3. Integration into github workflows
   Question: Should the unit tests be integrated into github actions as described in
   https://docs.github.com/en/actions/use-cases-and-examples/building-and-testing/building-and-testing-python
   ?