Parsing breaks when adding a closing bracket in a quoted key

[spapanik]

parsing breaks when the quoted key contains a closing bracket.

>>> import tomlkit
>>> tomlkit.parse("""
... ["["]
... foo = 1
... """)
{'[': {'foo': 1}}

>>> tomlkit.parse("""
... ["]"]
... foo = 1
... """)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/stephanos/.local/share/virtualenvs/tomlkit/lib/python3.8/site-packages/tomlkit/api.py", line 51, in parse
    return Parser(string).parse()
  File "/home/stephanos/.local/share/virtualenvs/tomlkit/lib/python3.8/site-packages/tomlkit/parser.py", line 153, in parse
    key, value = self._parse_table()
  File "/home/stephanos/.local/share/virtualenvs/tomlkit/lib/python3.8/site-packages/tomlkit/parser.py", line 946, in _parse_table
    cws, comment, trail = self._parse_comment_trail()
  File "/home/stephanos/.local/share/virtualenvs/tomlkit/lib/python3.8/site-packages/tomlkit/parser.py", line 314, in _parse_comment_trail
    raise self.parse_error(UnexpectedCharError, c)
tomlkit.exceptions.UnexpectedCharError: Unexpected character: '"' at line 2 col 3