`mock_snakemake` incompatible with `snakemake=8.14.0`

`snakemake` internal structure changed with recent update, causing this error:

```
ImportErorr: cannot import name 'ConfigSettings' from 'snakemake.settings'
```

Solution:

change

```
from snakemake.settings import ConfigSettings
```

to 
```
from snakemake.settings.types import ConfigSettings
```