Simplify regex in yelling.py

[bradleysigma]

Noticed the superfluous regex in https://www.youtube.com/live/6wFATYjMTQE?t=1376

[andrewj-brown]

This is honestly a little disappointing. You're a regular contributor. We have 18 open issues you could have put work into, and you yourself have an open PR needing changes (granted, unlikely to be merged anyway, for committee reasons, but still). Why are you wasting my review time and your coding time with a 3-character change? You're perfectly capable of, y'know, fulfilling the actual purpose of hacktoberfest and making positive contributions to the bot.

Hell, issue #160 is right up your alley, considering how much work you've put into the yelling cog. Why wouldn't you go do that?

If you want a concrete reason why I'm not merging this...

• it's polluting the git blame, and making it unclear who's fault this regex is (not that it's a particularly complicated regex, but on principle, git blame should always be useful & accurate)
• it's using more-specific regex syntax, which actually makes it less easily readable than using the language-agnostic [^\s] construct - we're not code golfing here
• it's sending me stupid emails and interrupting me on a day when I need to be doing actual work on my assignments
• and, it's sending a poor message to external or future contributors that we're rubber-stamping hacktoberfest bullshit PRs from people in the "in group", making it harder to argue the case that we shouldn't accept them next time someone else submits one.