Merge pull request #739 from ohbarye/dependabot/bundler/backend/nokogiri-1.13.6

Bump nokogiri from 1.13.3 to 1.13.6 in /backend

Author: ohbarye

backend/Gemfile.lock

@@ -104,7 +104,7 @@ GEM
     minitest (5.15.0)
     msgpack (1.4.5)
     nio4r (2.5.8)
-    nokogiri (1.13.3)
+    nokogiri (1.13.6)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     pg (1.3.5)