autoapi.not_readable error only on readthedocs

[c-randall]

I'm getting a [autoapi.not_readable] error every time I try to build my documentation on readthedocs. The error does not occur locally.

I even tried to just rebuild a previously successful documentation version. Without making any changes, I'm getting the same [autoapi.not_readable] error on these previously successful versions too. It occurs for every file in my package.

[dstansby]

For anyone looking for a pix, pinning astroid<4 in your dependencies should work.

This is a duplicate of #512 (or the other way round)

[AWhetter]

Closing as a duplicate of #512