Default values are not displayed for types other than string

[radao]

Describe the bug
Using type hints and enabling show_signature_annotations displays each parameters type correctly, but not default value unless its a string.

To Reproduce
Steps to reproduce the behavior:

1. Define a method such as def foo(a: str = 'hello', b: int = 10, c: bool = False, d: str = 'world') -> None
2. Enableshow_signature_annotations in your mkdocs.yml:

plugins:
  - mkdocstrings:
      handlers:
        python:
          rendering:
            show_signature_annotations: True

3. Observe in the generated docs only the string fields default values are displayed (ie a and d).

System (please complete the following information):

• mkdocs versions:

mkdocs==1.2
mkdocstrings==0.18.1
mkdocstrings-python==0.6.6

• Python version: 3.7
• OS: Linux

[pawamoy]

Confirmed on Python 3.7 (greater versions seem unaffected). Thanks for the report 🙂

[pawamoy]

Fixed in Griffe 0.14.1