slack.py 2.10.2: Merge with mainline

[trygveaa]

This is version 2.10.2 of slack.py (currently the most recent), copied over from the wee-slack repo.

Script info

• Script name: slack.py
• Version: 2.10.2
• Requirements: unchanged
• Min WeeChat version: unchanged
• Script tags: unchanged

Description

See https://github.com/wee-slack/wee-slack/releases/tag/v2.10.2

Checklist (script update)

• Author has been contacted
• Single commit, single file added
• Commit message format: script_name.py X.Y: …
• Script version and Changelog have been updated
• For Python script: works with Python 3 (Python 2 support is optional)
• Score 100 / 100 displayed by weechat-script-lint