Bump sprockets from 3.7.1 to 3.7.2 in /examples/rails5_app

Bumps [sprockets](http://getsprockets.org/) from 3.7.1 to 3.7.2.

Signed-off-by: dependabot[bot] <support@github.com>

examples/rails5_app/Gemfile.lock

@@ -42,7 +42,7 @@ GEM
     bcrypt (3.1.11)
     builder (3.2.3)
     byebug (9.0.6)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.5)
     debug_inspector (0.0.2)
     devise (4.2.0)
       bcrypt (~> 3.0)
@@ -86,7 +86,7 @@ GEM
       mini_portile2 (~> 2.1.0)
     orm_adapter (0.5.0)
     puma (3.7.1)
-    rack (2.0.1)
+    rack (2.0.7)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (5.0.2)
@@ -130,7 +130,7 @@ GEM
     spring-watcher-listen (2.0.1)
       listen (>= 2.7, < 4.0)
       spring (>= 1.2, < 3.0)
-    sprockets (3.7.1)
+    sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     sprockets-rails (3.2.0)