Add frozen string literal comment to files.

Add frozen string literal comment to files.

diff --git a/Gemfile b/Gemfile
index 2a5f647..df32188 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 group :development do
   gem 'translations-manager', git: 'https://github.com/discourse/translations-manager.git'
 end
diff --git a/bin/pull_translations.rb b/bin/pull_translations.rb
index 755a227..789ccaa 100755
--- a/bin/pull_translations.rb
+++ b/bin/pull_translations.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 # Usage:
 #   bundle install
diff --git a/lib/queries.rb b/lib/queries.rb
index d63efc9..a7878cc 100644
--- a/lib/queries.rb
+++ b/lib/queries.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Queries
   def self.default
     # WARNING: Edit the query hash carefully
@@ -421,8 +423,8 @@ class Queries
     WHERE CASE WHEN :include_pms THEN true ELSE t.archetype = 'regular' END
     AND t.deleted_at IS NULL
     AND p.deleted_at IS NULL
-    AND p.created_at::date >= :start_date 
-    AND p.created_at::date <= :end_date 
+    AND p.created_at::date >= :start_date
+    AND p.created_at::date <= :end_date
     AND p.post_number > 1
     )
 
diff --git a/plugin.rb b/plugin.rb
index 12489b2..1602b61 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # name: discourse-data-explorer
 # about: Interface for running analysis SQL queries on the live database
 # version: 0.2
diff --git a/spec/controllers/queries_controller_spec.rb b/spec/controllers/queries_controller_spec.rb
index 95130d6..0f97beb 100644
--- a/spec/controllers/queries_controller_spec.rb
+++ b/spec/controllers/queries_controller_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 describe DataExplorer::QueryController do

GitHub sha: 817a233c