files.upload is getting deprecated by Slack

[DestroyerAlpha]

Description

Check if we are using slack's file.upload API and migrate to newly suggested API for uploading files in slack.

(Optional) Slack's documentation

https://api.slack.com/methods/files.upload
files.upload is deprecated and will stop functioning on March 11, 2025. Use files.getUploadURLExternal and files.completeUploadExternal to upload files instead. Newly created apps will be unable to use files.upload beginning May 8, 2024. See Uploading files for more details on the process and this changelog for more on the deprecation.

[lorenzoaiello]

@DestroyerAlpha , There are currently two methods available in this package (UploadFileV2 and UploadFileV2Context) which should provide a path forward which require no token scope changes to transition to.

I'm not sure how many people are going to be affected or if there is interest in updating the existing UploadFile method to call UploadFileV2 under the hood to not break existing applications.