[Security] Bump sprockets from 2.12.4 to 2.12.5

Bumps [sprockets](https://github.com/rails/sprockets) from 2.12.4 to 2.12.5. **This update includes a security fix.**
- [Release notes](https://github.com/rails/sprockets/releases)
- [Changelog](https://github.com/rails/sprockets/blob/master/CHANGELOG.md)
- [Commits](rails/sprockets@v2.12.4...v2.12.5)

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

Author: dependabot-preview[bot]

Gemfile.lock

@@ -84,7 +84,7 @@ GEM
     jquery-rails (3.1.3)
       railties (>= 3.0, < 5.0)
       thor (>= 0.14, < 2.0)
-    json (2.3.1)
+    json (1.8.6)
     kaminari (0.16.3)
       actionpack (>= 3.0.0)
       activesupport (>= 3.0.0)
@@ -93,7 +93,7 @@ GEM
     method_source (0.8.2)
     mime-types (2.6.1)
     minitest (5.7.0)
-    multi_json (1.11.2)
+    multi_json (1.14.1)
     orm_adapter (0.5.0)
     pg (0.18.2)
     pry (0.10.1)
@@ -139,7 +139,7 @@ GEM
       rdoc (~> 4.0)
     slop (3.6.0)
     spring (1.3.6)
-    sprockets (2.12.4)
+    sprockets (2.12.5)
       hike (~> 1.2)
       multi_json (~> 1.0)
       rack (~> 1.0)