Fix rubocop issues in metanorma, git_template.rb

exe/metanorma

@@ -11,8 +11,10 @@ $:.unshift File.expand_path("../../lib", bin_file)
 # Fixes https://github.com/rubygems/rubygems/issues/1420
 require "rubygems/specification"
 
-class Gem::Specification
-  def this; self; end
+module Gem
+  class Specification
+    def this; self; end
+  end
 end
 
 # start up the CLI

lib/metanorma/cli/git_template.rb

@@ -10,16 +10,15 @@ def initialize(name, options = {})
 
       def remove!
         remove_template
-        return true
+        true
       end
 
       def download
         remove!
         clone_git_template(options[:repo])
-
       rescue Git::GitExecuteError
         UI.say("Invalid template reoository!")
-        return nil
+        nil
       end
 
       def find_or_download
@@ -86,7 +85,7 @@ def git_repos
           iso: "https://github.com/metanorma/mn-templates-iso",
           iec: "https://github.com/metanorma/mn-templates-iec",
           itu: "https://github.com/metanorma/mn-templates-itu",
-          ietf: "https://github.com/metanorma/mn-templates-ietf"
+          ietf: "https://github.com/metanorma/mn-templates-ietf",
         }
       end