Bump importmap-rails from 0.8.2 to 0.9.0

Bumps [importmap-rails](https://github.com/rails/importmap-rails) from 0.8.2 to 0.9.0.
- [Release notes](https://github.com/rails/importmap-rails/releases)
- [Commits](https://github.com/rails/importmap-rails/compare/v0.8.2...v0.9.0)

---
updated-dependencies:
- dependency-name: importmap-rails
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -79,7 +79,7 @@ GEM
       activesupport (>= 5.0)
     i18n (1.8.11)
       concurrent-ruby (~> 1.0)
-    importmap-rails (0.8.2)
+    importmap-rails (0.9.0)
       rails (>= 6.0.0)
     io-console (0.5.9)
     irb (1.3.7)
@@ -187,7 +187,7 @@ GEM
     sprockets (4.0.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
-    sprockets-rails (3.3.0)
+    sprockets-rails (3.4.1)
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)