Fix date parsing

Float microseconds format is already added in case the date ends with
floating points. Adding it always breaks other dates as well as those
with floating points.

Author: lhelwerd

gitlab3/__init__.py

@@ -345,7 +345,7 @@ def _convert_dates(self, data):
 
     def _convert_gitlab_date(self, datetime_str):
         """Convert GitLab datetime string to datetime object"""
-        fmt = '%Y-%m-%dT%H:%M:%S.%f'
+        fmt = '%Y-%m-%dT%H:%M:%S'
         offset = None
         if datetime_str.endswith('Z'):
             datetime_str = datetime_str[:-1]