Annotate past migrations with Rails version

Many migrations currently fail to run with:

> Directly inheriting from ActiveRecord::Migration is not supported.
> Please specify the Rails release the migration was written for:
>
>     class Example < ActiveRecord::Migration[4.2]

I've annotated those that I need to run with the Rails version at the
time each was committed:

    rake db:migrate:status \
    | grep --perl-regexp --only-matching '(?<=^  down    )\d{14}' \
    | while read -r id; do
      path="$(ls -1 db/migrate/${id}_*.rb)"
      version="$(git show "$(git log --diff-filter=A --pretty=format:%H -- "$path")":Gemfile.lock \
        | grep --perl-regexp --only-matching '(?<=^    rails \()\d+\.\d+(?=(\.\d+)+\))')"
      sed --in-place -e "s/\(< ActiveRecord::Migration\)$/\\1[$version]/" "$path"
    done

db/migrate/20170516190048_create_booths.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreateBooths < ActiveRecord::Migration
+class CreateBooths < ActiveRecord::Migration[4.2]
   def change
     create_table :booths do |t|
       t.string :title