Fix crtag length validation

[gogaz]

Changes Description

Current behaviour:

>>> player = api_client.get_player('8029R')
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "clashroyale/royaleapi/utils.py", line 30, in wrapper
    new_args.append(converter(a))
  File "clashroyale/royaleapi/utils.py", line 85, in crtag
    raise ValueError('Tag ({}) too short, length {}, expected 3'.format(tag[3:], len(tag[3:])))
ValueError: Tag (9R) too short, length 2, expected 3

Expected behaviour:

>>> player = api_client.get_player('8029R')
>>> player.name
'mickey'

Type of PR

• [x] Bug Fix
• [ ] Feature Addition

Checklist

• [ ] Docstrings added (NumpyDoc)
• [ ] If necessary, add to the documentation files
• [x] Add to the CHANGELOG file
• [x] Tox checked