gpx_parser: Fix crash if gpx doesn't contain timings

Signed-off-by: Thomas Klaehn <thomas.klaehn@u-blox.com>

example-gpx-parser

@@ -24,7 +24,7 @@ def main():
                 max_day = (datetime.date(year + 1, 1, 1) - datetime.timedelta(days=1)).day
             else:
                 max_day = (datetime.date(year, month + 1, 1) - datetime.timedelta(days=1)).day
-            for day in range(1, max_day):
+            for day in range(1, max_day + 1):
                 date_tracks = tracks.get(year, month, day)
                 date_date = datetime.datetime(year, month, day)
                 date_dist = 0.0