Updating a json object fails if the value of a key is boolean

[Andrewnopoulos]

Related to #47

Steps to reproduce:

from jsonpath_ng import parse
selector = '$.*.number'
data = {
    'foo': ['abc', 'def'],
    'bar': {'number': 123456},
    'boolean': True
}
val = '98765'
expr = parse(selector)
expr.update(data, val)

Expected

'number' field to be updated to '98765'.

Observed

  File "/home/andrew/test.py", line 12, in <module>
    expr.update(data, val)
  File "/home/andrew/jsonpath_ng/jsonpath.py", line 261, in update
    self.right.update(datum.value, val)
  File "/home/andrew/jsonpath_ng/jsonpath.py", line 526, in update
    if field in data:
TypeError: argument of type 'bool' is not iterable