Ensure bin/setup works

Closes #1224

It's unclear why we need to run migrations, since we were originally
calling [db:prepare][dbp] which does the following:

> If the database exists but the tables have not been created, the
command will load the schema, run any pending migrations, dump the
updated schema, and finally load the seed data. See the Seeding Data
documentation for more details.

However, I found that calling `db:migrate` in the application template
worked.

[dbp]: https://guides.rubyonrails.org/active_record_migrations.html#preparing-the-database

lib/install/web.rb

@@ -35,7 +35,7 @@ def apply_template!
       run "bundle install"
 
       generate "suspenders:install:web"
-      rails_command "db:prepare"
+      rails_command "db:migrate"
 
       say "\nCongratulations! You just pulled our suspenders."
     end