Merge pull request #642 from coderdojo-japan/dependabot/bundler/loofah-2.4.0

Bump loofah from 2.3.1 to 2.4.0

Author: yasulab

Gemfile.lock

@@ -186,7 +186,7 @@ GEM
     listen (3.2.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    loofah (2.3.1)
+    loofah (2.4.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     mail (2.7.1)