Revert "Rollback to minitest-5.27.0"

This reverts commit 8d097bc.

Author: hsbt

NEWS.md

@@ -373,7 +373,7 @@ The following default gems are updated.
 
 The following bundled gems are updated.
 
-* minitest 5.27.0
+* minitest 6.0.0
 * power_assert 3.0.1
   * 2.0.5 to [v3.0.0][power_assert-v3.0.0], [v3.0.1][power_assert-v3.0.1]
 * rake 13.3.1

gems/bundled_gems

@@ -6,7 +6,7 @@
 # - revision: revision in repository-url to test
 #   if `revision` is not given, "v"+`version` or `version` will be used.
 
-minitest            5.27.0  https://github.com/minitest/minitest
+minitest            6.0.0  https://github.com/minitest/minitest
 power_assert        3.0.1   https://github.com/ruby/power_assert
 rake                13.3.1  https://github.com/ruby/rake
 test-unit           3.7.5   https://github.com/test-unit/test-unit