add dependencies for readthedoc

[TiansuYu]

Description

We need sphinx-autoapi for building read the doc in squirrel-core.

Also removed requirements.parquet.in which is not used (and misleading).

Fixes # issue

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring including code style reformatting
• Other (please describe):

Checklist:

• Lint and unit tests pass locally with my changes
• I have kept the PR small so that it can be easily reviewed
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• All dependency changes have been reflected in the pip requirement files.

[winfried-ripken]

LGTM