Bump loofah from 2.2.3 to 2.3.1 in /rails/iwato

Bumps [loofah](https://github.com/flavorjones/loofah) from 2.2.3 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@v2.2.3...v2.3.1)

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

rails/iwato/Gemfile.lock

@@ -66,7 +66,7 @@ GEM
     coffee-script-source (1.12.2)
     commonjs (0.2.7)
     concurrent-ruby (1.1.3)
-    crass (1.0.4)
+    crass (1.0.5)
     erubi (1.7.1)
     execjs (2.7.0)
     ffi (1.9.25)
@@ -105,7 +105,7 @@ GEM
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
-    loofah (2.2.3)
+    loofah (2.3.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     mail (2.7.1)
@@ -115,13 +115,13 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
     mini_mime (1.0.1)
-    mini_portile2 (2.3.0)
+    mini_portile2 (2.4.0)
     minitest (5.11.3)
     multi_json (1.13.1)
     mysql2 (0.4.10)
     nio4r (2.3.1)
-    nokogiri (1.8.5)
-      mini_portile2 (~> 2.3.0)
+    nokogiri (1.10.5)
+      mini_portile2 (~> 2.4.0)
     paper_trail (8.1.2)
       activerecord (>= 4.2, < 5.2)
       request_store (~> 1.1)