AttributeError: 'NoneType' object has no attribute 'loader'

### Conda-forge documentation

- [X] I could not solve my problem using the conda-forge documentation.

### Installed packages

```shell
staged-recipes
```

### Environment info

```shell
it is on staged-recipes
```

### Issue

Please have a look on this new package I added
https://github.com/conda-forge/staged-recipes/pull/22478

I can build this only with a fixation of setuptools to 65.5.1

I had a different problem with setuptools and it was only a guess to try that. So yes I can build the package but I want do that also in the future.