Fix rubocop offenses.

lib/math_renderer.rb

@@ -1,6 +1,6 @@
 # the idea here is to support server rendering
 # there is a node example and we could inject this in a post processing job
 class DiscourseMath::MathRenderer
-  def self.render(mathjax, options={})
+  def self.render(mathjax, options = {})
   end
 end