Fix "from pycallnumber import *"

[tdilauro]

Importing with

from pycallnumber import *

results in TypeError:

Connected to pydev debugger (build 182.4505.26)
raceback (most recent call last):
  File "callnumber.py", line 3, in <module>
    from pycallnumber import *
  File "<frozen importlib._bootstrap>", line 1031, in _handle_fromlist
  File "<frozen importlib._bootstrap>", line 1026, in _handle_fromlist
TypeError: Item in pycallnumber.__all__ must be str, not module

If present, all must be a sequence of strings.[1]

• Changed items in all to strings.
• Ran tests (passed).
• Bumped version number.

[1] See section https://docs.python.org/3/reference/simple_stmts.html#the-import-statement

[jthomale]

👍 Awesome, thanks for catching that.