Rubocop cleanup

Author: technion

Steepfile

@@ -4,7 +4,7 @@ target :lib do
   signature "sig"
 
   check "argon2.rb"
-  check "lib"                       # Directory name
+  check "lib" # Directory name
   ignore "lib/argon2/ffi_engine.rb"
   ignore "lib/argon2/errors.rb"
 end