fix "invalid escape sequence" errors

[amakea]

Script info

• Script name:  twitch
• Version: 1.0.1

• Requirements: 

• Min WeeChat version: 

• Script tags: 

Description

When loading up the latest version of twitch.py in weechat I am given the following errors...

python: stdout/stderr (?): /home/user/.local/share/weechat/python/twitch.py:356: SyntaxWarning: invalid escape sequence '\s'
python: stdout/stderr (?):   bn=tags['ban-reason'].replace('\s',' ')
python: stdout/stderr (?): /home/user/.local/share/weechat/python/twitch.py:364: SyntaxWarning: invalid escape sequence '\s'
python: stdout/stderr (?):   bn=tags['ban-reason'].replace('\s',' ')
python: stdout/stderr (?): /home/user/.local/share/weechat/python/twitch.py:461: SyntaxWarning: invalid escape sequence '\s'
python: stdout/stderr (?):   msg = tags['system-msg'].replace('\s',' ')

I made some minor changes to make them go away.

Checklist (new script)

• [ ] Single commit, single file added
• [ ] Commit message: New script name.py: short description…
• [ ] No similar script already exists
• [ ] Name: max 32 chars, only lower case letters, digits and underscores
• [ ] Unique name, does not already exist in repository
• [ ] No shebang on the first line
• [ ] Comment in script with name/pseudo, e-mail and license using SPDX tags (see Contributing guide)
• [ ] Only English in code/comments
• [ ] Pure WeeChat API used, no extra API
• [ ] Function hook_url, hook_process or hook_process_hashtable is used for any blocking call
• [ ] For Python script: works with Python 3 (Python 2 support is optional)
• [ ] Score 100 / 100 displayed by weechat-script-lint

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

Checklist (script deletion)

• [ ] Author has been contacted
• [ ] Single commit, single file deleted
• [ ] Commit message format: Remove script name.py with reasons in description