build(deps): bump sprockets from 3.7.2 to 3.7.3

Bumps [sprockets](https://github.com/rails/sprockets) from 3.7.2 to 3.7.3.
- [Release notes](https://github.com/rails/sprockets/releases)
- [Changelog](https://github.com/rails/sprockets/blob/v3.7.3/CHANGELOG.md)
- [Commits](rails/sprockets@v3.7.2...v3.7.3)

---
updated-dependencies:
- dependency-name: sprockets
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -1050,7 +1050,8 @@ GEM
       spring (>= 0.9.1)
     spring-commands-rubocop (0.4.0)
       spring (>= 1.0)
-    sprockets (3.7.2)
+    sprockets (3.7.3)
+      base64
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     sprockets-rails (3.4.2)