Remove ExpressionParser and use the amazing RuboCop::AST::NodePattern

Author: Jônatas Davi Paganini

fast.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |spec|
   spec.executables   = %w[fast fast-experiment]
   spec.require_paths = %w[lib experiments]
 
-  spec.add_dependency 'astrolabe'
+  spec.add_dependency 'rubocop-ast'
   spec.add_dependency 'coderay'
   spec.add_dependency 'parallel'
   spec.add_dependency 'parser'