fix: change the filename SQLite3 in accordance with Rails 7.1

[tnir]

In Rails 7.1, the database filename for SQLite3 was changed: see https://github.com/rails/rails/pull/46699

• Upstream: https://github.com/railsgirls/guides.railsgirls.com/pull/578
• Ref: https://github.com/rails/rails/pull/46699
• Acknowledge: @rlis12099