Update bundled gems list at 2023-05-25

NEWS.md

@@ -69,7 +69,7 @@ The following default gems are updated.
 The following bundled gems are updated.
 
 * minitest 5.18.0
-* test-unit 3.5.8
+* test-unit 3.5.9
 * rbs 3.1.0
 * typeprof 0.21.7
 * debug 1.8.0

gems/bundled_gems

@@ -8,7 +8,7 @@
 minitest        5.18.0  https://github.com/minitest/minitest
 power_assert    2.0.3   https://github.com/ruby/power_assert
 rake            13.0.6  https://github.com/ruby/rake
-test-unit       3.5.8   https://github.com/test-unit/test-unit
+test-unit       3.5.9   https://github.com/test-unit/test-unit
 rexml           3.2.5   https://github.com/ruby/rexml
 rss             0.2.9   https://github.com/ruby/rss
 net-ftp         0.2.0   https://github.com/ruby/net-ftp