Update allowed types for instance_vals in query_by_values

Currently the `query_by_values` method lists four allowable input types for the `instance_vals` parameter: `pd.Dataframe, pd.Series, list[str] or str`

The current Featuretools code will only call this method with a `pd.Series` input during normal operation, although there are several unit tests that call the method with a list used to specify `instance_vals`. There is code in the `_vals_to_series` method that handles the conversion of these different types. As there is no current need in Featuretools for this code to handle `pd.DataFrame` or `str` inputs, these types could be removed.

Optionally, support for list input could be dropped if the corresponding unit tests are updated, which would leave only `pd.Series` as a valid input type for `instance_vals`.

Making these changed would simplify the code base and test suite. Any users that might be calling `query_by_values` directly with one of the dropped types, would simply have to convert their values to a pd.Series before the call, but otherwise the functionality and output would remain unchanged.