Replace =~ with #matches?. #208.

=~ made sense when we were passing it through to a regex, but we're no
longer doing that: TagMatcher looks at individual tags and returns a
value that *looks* like what you get out of #=~ but really isn't that
meaningful.  Probably a good idea to not subvert convention like this
and instead use a name with guessable intent.

app/models/glitch/keyword_mute.rb

@@ -62,8 +62,8 @@ class Glitch::KeywordMute < ApplicationRecord
       format('keyword_mutes:regex:text:%s', account_id)
     end
 
-    def =~(str)
-      regex =~ str
+    def matches?(str)
+      !!(regex =~ str)
     end
 
     private
@@ -82,8 +82,8 @@ class Glitch::KeywordMute < ApplicationRecord
       format('keyword_mutes:regex:tag:%s', account_id)
     end
 
-    def =~(tags)
-      tags.pluck(:name).detect { |n| regex =~ n }
+    def matches?(tags)
+      tags.pluck(:name).any? { |n| regex =~ n }
     end
 
     private