[Security] Bump loofah from 2.3.0 to 2.3.1

Bumps [loofah](https://github.com/flavorjones/loofah) from 2.3.0 to 2.3.1. **This update includes a security fix.**
- [Release notes](https://github.com/flavorjones/loofah/releases)
- [Changelog](https://github.com/flavorjones/loofah/blob/master/CHANGELOG.md)
- [Commits](flavorjones/loofah@v2.3.0...v2.3.1)

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

Author: dependabot-preview[bot]

Gemfile.lock

@@ -78,7 +78,7 @@ GEM
     concurrent-ruby (1.1.5)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
-    crass (1.0.4)
+    crass (1.0.5)
     dalli (2.7.10)
     debug_inspector (0.0.3)
     domain_name (0.5.20190701)
@@ -157,7 +157,7 @@ GEM
       activesupport (>= 4.0)
       logstash-event (~> 1.2.0)
       request_store
-    loofah (2.3.0)
+    loofah (2.3.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     mail (2.7.1)