Fix sexadecimal number regex

[doino-gretchenliev]

The underlaying ruamel.yaml library is wrongfully detecting ipam map as CommentedSeq and so the regex match, inside fix_sexadecimal_numbers, is failing when trying to process ordereddict([('subnet', '172.16.0.0/16')]) instead of string object. So parsing every value to str is a workaround and doesn't break any functionality. Here is the error without the fix:

Traceback (most recent call last):
  File "./bin/compose_format", line 35, in <module>
    if not formatter.format(path, replace=args.replace, strict=not args.non_strict):
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 68, in format
    formatted = self.format_string(data, replace=replace, strict=strict)
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 78, in format_string
    data = self.reorder(load(data, RoundTripLoader), strict=strict)
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 99, in reorder
    ComposeFormat.reorder(item, strict)
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 99, in reorder
    ComposeFormat.reorder(item, strict)
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 99, in reorder
    ComposeFormat.reorder(item, strict)
  [Previous line repeated 1 more time]
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 103, in reorder
    data[i] = ComposeFormat.fix_sexadecimal_numbers(value)
  File "/usr/local/lib/python3.7/site-packages/compose_format/__init__.py", line 114, in fix_sexadecimal_numbers
    match = re.match(SEXADECIMAL_NUMBER, value)
  File "/usr/local/lib/python3.7/re.py", line 173, in match
    return _compile(pattern, flags).match(string)
TypeError: expected string or bytes-like object