Merge pull request #2389 from ruby/dependabot/bundler/steep/test-unit-3.6.8

Bump test-unit from 3.6.7 to 3.6.8 in /steep

Author: soutaro

steep/Gemfile.lock

@@ -73,7 +73,7 @@ GEM
     strscan (3.1.2)
     terminal-table (4.0.0)
       unicode-display_width (>= 1.1.1, < 4)
-    test-unit (3.6.7)
+    test-unit (3.6.8)
       power_assert
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)