TYP deprecate_nonkeyword_arguments
If we have
```python
import pandas as pd

reveal_type(pd.Series(range(3)).interpolate('linear'))
```

then on master we get:
```console
$ mypy t.py 
t.py:3: note: Revealed type is 'Any'
```
while here
```console
$ mypy t.py 
t.py:3: note: Revealed type is 'Union[pandas.core.series.Series, None]'
```
thanks @MarcoGorelli 