style(rubocop): fix all safe auto correctable offenses

config/initializers/smtp_extensions.rb

@@ -1,10 +1,13 @@
 class Net::SMTP::Response
+
   def message
     @string
   end
+
 end
 
 class Net::SMTP
+
   attr_accessor :source_address
 
   def secure_socket?
@@ -19,7 +22,7 @@ class Net::SMTP
   #
   def rset
     @error_occurred = false
-    getok('RSET')
+    getok("RSET")
   end
 
   def rset_errors
@@ -29,6 +32,7 @@ class Net::SMTP
   private
 
   def tcp_socket(address, port)
-    TCPSocket.open(address, port, self.source_address)
+    TCPSocket.open(address, port, source_address)
   end
+
 end