Update dependency minitest to v6

Author: renovate[bot]

Gemfile

@@ -129,7 +129,7 @@ group :test do
   # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
   gem 'capybara'
   gem 'climate_control'
-  gem 'minitest', '< 6'
+  gem 'minitest', '< 7'
   gem 'mocha'
   gem 'selenium-webdriver'
   gem 'simplecov'

Gemfile.lock

@@ -549,7 +549,7 @@ DEPENDENCIES
   http
   importmap-rails
   jbuilder
-  minitest (< 6)
+  minitest (< 7)
   mitlibraries-theme!
   mocha
   omniauth