f-string parser: Update parentheses errors

[pablogsal]

There is a bunch of tests that fail because the tokenizer error for mismatched parentheses is different. For example:

FAIL: test_compile_time_concat (test.test_fstring.TestCase) (str="f'{3' f'}'")\n----------------------------------------------------------------------
  File "<string>", line 1
    f'{3' f'}'
        ^
SyntaxError: expected '}'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/pablogsal/github/python/f-string-grammar/Lib/test/test_fstring.py", line 32, in assertAllRaise
    with self.assertRaisesRegex(exception_type, regex):
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: "f-string: expecting '}'" does not match "expected '}' (<string>, line 1)"

we need to update these tests.