Bump loofah from 2.2.2 to 2.3.1

Bumps [loofah](https://github.com/flavorjones/loofah) from 2.2.2 to 2.3.1.
- [Release notes](https://github.com/flavorjones/loofah/releases)
- [Changelog](https://github.com/flavorjones/loofah/blob/master/CHANGELOG.md)
- [Commits](flavorjones/loofah@v2.2.2...v2.3.1)

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

Author: dependabot[bot]

Gemfile.lock

@@ -53,7 +53,7 @@ GEM
     coffee-script-source (1.12.2)
     concurrent-ruby (1.1.5)
     connection_pool (2.2.2)
-    crass (1.0.4)
+    crass (1.0.6)
     debase (0.2.1)
       debase-ruby_core_source
     debase-ruby_core_source (0.10.2)
@@ -73,7 +73,7 @@ GEM
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
-    loofah (2.2.2)
+    loofah (2.4.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     mail (2.7.0)