Bump sprockets from 3.7.2 to 4.2.1

Bumps [sprockets](https://github.com/rails/sprockets) from 3.7.2 to 4.2.1.
- [Release notes](https://github.com/rails/sprockets/releases)
- [Changelog](https://github.com/rails/sprockets/blob/main/CHANGELOG.md)
- [Commits](rails/sprockets@v3.7.2...v4.2.1)

---
updated-dependencies:
- dependency-name: sprockets
  dependency-type: indirect
  update-type: version-update:semver-major
...

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

Gemfile.lock

@@ -225,9 +225,9 @@ GEM
     sassc-embedded (1.69.1)
       sass-embedded (~> 1.69)
     servolux (0.13.0)
-    sprockets (3.7.2)
+    sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
+      rack (>= 2.2.4, < 4)
     temple (0.10.3)
     thor (0.20.3)
     tilt (2.0.11)