Replace `match?` with `match` for backwards compatibility with Ruby 2.3

app/models/channel.rb

@@ -41,7 +41,7 @@ class DiscourseChat::Channel < DiscourseChat::PluginModel
 
     data.each do |key, value|
       regex_string = params.find{|p| p[:key] == key}[:regex]
-      if !Regexp.new(regex_string).match?(value)
+      if !Regexp.new(regex_string).match(value)
         errors.add(:data, "data.#{key} is invalid")
       end
 

spec/models/channel_spec.rb

@@ -78,7 +78,7 @@ RSpec.describe DiscourseChat::Channel do
     end
 
     it 'disallows invalid data' do
-      channel2 = DiscourseChat::Channel.new(provider:"dummy2", data:{val:''})
+      channel2 = DiscourseChat::Channel.new(provider:"dummy2", data:{val:'  '})
       expect(channel2.valid?).to eq(false)
     end