Bump slim-rails from 3.1.3 to 3.2.0

Bumps [slim-rails](https://github.com/slim-template/slim-rails) from 3.1.3 to 3.2.0.
- [Release notes](https://github.com/slim-template/slim-rails/releases)
- [Changelog](https://github.com/slim-template/slim-rails/blob/master/CHANGELOG.md)
- [Commits](slim-template/slim-rails@v3.1.3...v3.2.0)

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

Gemfile.lock

@@ -309,13 +309,13 @@ GEM
       skylight-core (= 3.0.0)
     skylight-core (3.0.0)
       activesupport (>= 4.2.0)
-    slim (3.0.9)
+    slim (4.0.1)
       temple (>= 0.7.6, < 0.9)
-      tilt (>= 1.3.3, < 2.1)
-    slim-rails (3.1.3)
+      tilt (>= 2.0.6, < 2.1)
+    slim-rails (3.2.0)
       actionpack (>= 3.1)
       railties (>= 3.1)
-      slim (~> 3.0)
+      slim (>= 3.0, < 5.0)
     spring (2.0.2)
       activesupport (>= 4.2)
     spring-watcher-listen (2.0.1)