Gemfile.lock in u-struct-0.3.1 vs Gemfile.lock in u-struct-0.4.0

@@ -1,8 +1,8 @@
 PATH
   remote: .
   specs:
-    u-struct (0.3.1)
+    u-struct (0.4.0)
 
 GEM
   remote: https://rubygems.org/
   specs:
     minitest (5.14.4)