[cristianchiriac]

Description

Covers item 3 of #2624.

• Checklists: send_checklist and edit_message_checklist put the InputChecklist object into the request parameters as is. requests then sends str(checklist), i.e. <telebot.types.InputChecklist object at ...>, instead of the JSON the API expects. Both now send checklist.to_json(), like reply_parameters.to_json() next to them.
• replace_sticker_in_set: it sent sticker.to_json() with a GET request. For an InputSticker built from an InputFile, the JSON refers to the file as attach://<name>, but the file itself was never sent. It now uses sticker.convert_input_sticker() and POSTs the files, the same as add_sticker_to_set.

The same changes are in apihelper.py and asyncio_helper.py. Items 1 and 2 of #2624 (rich message media uploads) are not touched.

Describe your tests

New tests in tests/test_apihelper_95.py replace apihelper._make_request / asyncio_helper._process_request and check what would be sent:

• the checklist parameter of send_checklist and edit_message_checklist is a JSON string with the checklist's title and tasks (sync and async);
• replace_sticker_in_set with an InputFile sticker sends the file under the name the attach:// reference uses, with method='post' (sync and async).

All three tests fail without the change and pass with it. pytest tests --ignore=tests/test_telebot.py: 290 passed, 2 skipped.

Python version: 3.12

OS: Windows 11

Checklist:

• I added/edited example on new feature/change (if exists)
• My changes won't break backward compatibility
• I made changes both for sync and async

[Copilot]

🟢 Approval recommended

The focused fixes follow existing helper patterns, include regression coverage, and have no identified blocking issues.

No open issues 🎉

What changed in this PR

Addresses item 3 of #2624 by fixing checklist serialization and replacement sticker uploads in both request helpers.

Changes:

• Serialize checklists as JSON for send and edit requests.
• Upload replacement sticker files using multipart POST requests.
• Add regression tests for synchronous and asynchronous helpers.

File	Description
tests/​test_apihelper_95.py	Tests checklist serialization and sticker uploads.
telebot/​asyncio_helper.py	Fixes asynchronous serialization and uploads.
telebot/​apihelper.py	Applies matching synchronous fixes.

_{Review effort: Balanced}

[Badiboy]

LGTM, thank you.