Wagatil v2.11 has dropped support for unidecode

[vinodMS]

Seems like the util here is still referencing to unidecode which is no longer supported and included in wagtail v2.11 , hence installing the new version of WSF throws an error

  File "/usr/local/lib/python3.8/site-packages/wagtailstreamforms/utils/general.py", line 2, in <module>
    from unidecode import unidecode
ModuleNotFoundError: No module named 'unidecode'

Solution can be,

1. Add unidecode as a dependency to setup.py or
2. Use something like safe_snake_case from wagtail core util instead of unidecode.