Fix DeprecationWarning when encoding StripeObject metadata (fixes #1651)

[praniketkw]

Fixes #1651

Why?

When updating metadata on resources like invoices, users encountered a DeprecationWarning even though they were using the public API correctly. The warning was triggered internally when the encoder checked for the deprecated stripe_id property on StripeObject instances. While the deprecation warning serves an important purpose for direct user access to stripe_id, it should not be shown for internal library usage.

What?

• Modified the _api_encode function in stripe/_encode.py to suppress DeprecationWarning when internally accessing the stripe_id property.
• Added warnings.catch_warnings() context managers around both the hasattr check and the property access to prevent warnings from bubbling up to users during internal encoding operations.
• Preserved the deprecation warning for direct user access to stripe_id while silencing it only for internal library usage.
• Updated tests to verify that no deprecation warnings are raised during encoding operations while maintaining all existing encoding behavior.
• The approach maintains the intended deprecation strategy while fixing the user experience issue where legitimate API usage triggered internal warnings.

[ramya-stripe]

@praniketkw Can you also update the PR description based on the new approach?

[praniketkw]

@ramya-stripe Done!

[ramya-stripe]

Hey @praniketkw

Just thought of an alternative with a smaller footprint. Can you try this and see if it works?

elif hasattr(value, "stripe_id")
   yield (key, getattr(value, "id"))

[praniketkw]

Thanks for the suggestion @ramya-stripe! I implemented your approach using getattr(value, "id") instead of value.stripe_id.

I had to wrap the hasattr(value, "stripe_id") check in warnings.catch_warnings() since hasattr itself triggers the deprecation warning. Also added a check for getattr(value, "id") is not None to handle edge cases properly.

The implementation now uses your approach while ensuring no warnings bubble up during internal encoding. Let me know if this looks good!