Add missing rakefile for rake release task

Add missing rakefile for rake release task

diff --git a/Gemfile.lock b/Gemfile.lock
index 3e4e74f..d0c0625 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    discourse_mail_receiver (1.0.0)
+    discourse_mail_receiver (4.0.2)
       mail (~> 2.7.1)
 
 GEM
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..cf5a5a6
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,12 @@
+#!/usr/bin/env rake
+# frozen_string_literal: true
+require 'bundler'
+
+begin
+  Bundler.setup :default, :development
+  Bundler::GemHelper.install_tasks
+rescue Bundler::BundlerError => error
+  $stderr.puts error.message
+  $stderr.puts "Run `bundle install` to install missing gems"
+  exit error.status_code
+end

GitHub sha: 9fa13939