Validation of time data fails

[Deleted user]

E.g.

2017-06-24R 06:12:04

leads to

[2019-10-08 12:29:52,827] ERROR in app: Exception on /preview [POST]
Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/flask/app.py", line 2446, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/lib/python3.7/site-packages/flask/app.py", line 1951, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/lib/python3.7/site-packages/flask/app.py", line 1820, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/lib/python3.7/site-packages/flask/app.py", line 1949, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/lib/python3.7/site-packages/flask/app.py", line 1935, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/sebastianw/dev/intelmq-webinput-csv/intelmq_webinput_csv/bin/backend.py", line 324, in preview
    parsed = dateutil.parser.parse(value)
  File "/usr/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 1358, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "/usr/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 649, in parse
    raise ValueError("Unknown string format:", timestr)
ValueError: ('Unknown string format:', '2017-06-24R 06:12:04')