Add thor to Gemfile directly (#8467)

It's a common dependency, but just in case

Gemfile

@@ -7,6 +7,7 @@ gem 'pkg-config', '~> 1.3'
 
 gem 'puma', '~> 3.11'
 gem 'rails', '~> 5.2.1'
+gem 'thor', '~> 0.20'
 
 gem 'hamlit-rails', '~> 0.2'
 gem 'pg', '~> 1.0'

Gemfile.lock

@@ -752,6 +752,7 @@ DEPENDENCIES
   stoplight (~> 2.1.3)
   streamio-ffmpeg (~> 3.0)
   strong_migrations (~> 0.2)
+  thor (~> 0.20)
   tty-command (~> 0.8)
   tty-prompt (~> 0.16)
   twitter-text (~> 1.14)