Update 3 files

- /Gemfile
- /.gitlab-ci.yml
- /Live2dHistoire/live2d/js/message.js

Gemfile

@@ -1,5 +1,5 @@
 source "https://rubygems.org"
-gem "jekyll"
+gem "jekyll" == 3.9.3
 group :jekyll_plugins do
   gem "jekyll-gist"
   gem "jekyll-coffeescript"