Upgrade test suite to use maxitest

Gemfile

@@ -18,7 +18,7 @@ gem "after_commit_everywhere"
 gem "yard"
 
 group :test do
-  gem "minitest"
+  gem "maxitest"
   gem "simplecov"
 end
 

test/helper.rb

@@ -4,7 +4,8 @@ require "bundler/setup"
 Bundler.require(:default, :test)
 
 require "minitest/pride"
-require "minitest/autorun"
+require "maxitest/autorun"
+# require "maxitest/threads"
 
 $TESTING = true
 # disable minitest/parallel threads