Mastodon v4.1.4

$ sudo su - mastodon
$ cd ./live
$ git fetch && git checkout v4.1.4
$ bundle install
$ yarn install
$ RAILS_ENV=production bundle exec rails assets:precompile

〜省略〜

  location ~ ^/assets/ {
    add_header Cache-Control "public, max-age=2419200, must-revalidate";
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains";
    try_files $uri =404;

# 以下の２行を追加
    add_header Content-Security-Policy: default-src 'none'; form-action 'none';
    add_header X-Content-Type-Options nosniff;
  }

〜省略〜