filter_by supports list fix

[Akm0d]

What does this PR do?

filter_by supports list

What issues does this PR fix or reference?

closes #39709

Commits signed with GPG?

Yes

Tests written

Yes

[dwoz]

@Akm0d Why is key sometimes not a str? When it isn't a str, what is it... a list?

In general, we want to avoid arguments that can have multiple types.

[Akm0d]

@Akm0d Why is key sometimes not a str? When it isn't a str, what is it... a list?

In general, we want to avoid arguments that can have multiple types.

The discussion in issue #39709 requests that filter_by support a list as a key. It could be that this change belongs further up in the filter_by function, but the line of code that errored in the issue was in this function man_shrugging

[dwoz]

@Akm0d Why is key sometimes not a str? When it isn't a str, what is it... a list?
In general, we want to avoid arguments that can have multiple types.

The discussion in issue #39709 requests that filter_by support a list as a key. It could be that this change belongs further up in the filter_by function, but the line of code that errored in the issue was in this function man_shrugging

I think it's worth making sure key will be a consistent type.

[sagetherage]

@Akm0d can you fix the merge conflict here, please?