replace ClimaBot for Slack file upload

[juliasloan25]

Slack will stop supporting their files.upload API on March 11, 2025. Our ClimaBot uses this interface to upload files to Slack, e.g. for our coupler report channel. We'll need to find an alternative to this

From Slack:

A workspace that you administer contains apps or integrations that recently used the files.upload web API method. We want to inform you about an important change coming to support for the files.upload API.

March 11, 2025

• Support for the files.upload API for all apps will be discontinued.

To prepare for this change, we recommend that app owners migrate away from files.upload and instead use the combination of files.getUploadURLExternal and files.completeUploadExternal. You can also leverage Slack's SDKs to help transition to this new way of uploading files by visiting our api.slack page.

If the apps using the files.upload API are not updated to the method above, file uploads from those apps in your workspace or organization will no longer work beginning on March 11, 2025. To view a list of apps in your workspace impacted by this change, click below: