Suppress "string returned by #{symbol} will be frozen in the future" warnings

[kou]

For example:

https://github.com/red-data-tools/charty/actions/runs/14327259034/job/40155029515#step:12:1596

pycall-1.5.2/lib/pycall/pyobject_wrapper.rb:37: warning: string returned by :index=.to_s will be frozen in the future

This warnings is started from Ruby 3.4.

[kou]

@mrkn Should we fix CI failures before this?

[mrkn]

@kou

Should we fix CI failures before this?

The answer is yes if we can.

The CI failures are corresponding to the spec change of begin-less ranges in Ruby 3.4. As I wrote in the comment in #191, we need to decide how to emulate Python's slice(None, None, -1) in Ruby >= 3.4.

Do you have any idea?

[mrkn]

@kou I'm trying to fix CI in #191. Wait a moment.

[kou]

Ah, I understand.

I'll add a comment to #191.

[kou]

+1