Fix #9436, #9471: autodoc: crashed if autodoc_class_signature = "separated"

[tk0miya]

Feature or Bugfix

• Bugfix

Purpose

• A list should be used for special-members option instead of set.
• refs: 4.1.0, autodoc_class_signature = "separated" set bug #9436, New autodoc_class_signature config option gives an exception #9471

[tk0miya]

Note: I reproduced the error with this Dockerfile:

FROM python:3.9-slim

RUN apt update; apt install -y build-essential curl git unzip vim
RUN git clone https://github.com/miohtama/capitalgram-onchain-dex-quant-data
WORKDIR /capitalgram-onchain-dex-quant-data/docs/
RUN pip3 install Sphinx
RUN pip3 install sphinx_rtd_theme
RUN pip3 install nbsphinx
RUN pip3 install sphinx_sitemap
RUN apt install -y pandoc
RUN pip3 install ..
RUN echo '' >> source/conf.py
RUN echo 'autodoc_class_signature = "separated"' >> source/conf.py
RUN make html