Bump sprockets from 3.7.0 to 4.0.0 (#2)

Bumps [sprockets](https://github.com/rails/sprockets) from 3.7.0 to 4.0.0.
- [Release notes](https://github.com/rails/sprockets/releases)
- [Changelog](https://github.com/rails/sprockets/blob/master/CHANGELOG.md)
- [Commits](rails/sprockets@v3.7.0...v4.0.0)

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -42,7 +42,7 @@ GEM
       public_suffix (~> 2.0, >= 2.0.2)
     arel (7.1.4)
     builder (3.2.2)
-    concurrent-ruby (1.0.2)
+    concurrent-ruby (1.1.5)
     descendants_tracker (0.0.4)
       thread_safe (~> 0.3, >= 0.3.1)
     diff-lcs (1.2.5)
@@ -151,7 +151,7 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.0)
-    sprockets (3.7.0)
+    sprockets (4.0.0)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     sprockets-rails (3.2.0)