CI: Pin power_assert to v2.x to drop support for Ruby < 3.1

taketo1113 · taketo1113 · commit c8b101e7ffcc · 2025-11-05T13:11:43.000+09:00
diff --git a/Gemfile b/Gemfile
@@ -5,4 +5,5 @@ gemspec
 gem "rake"
 gem "test-unit"
 gem "test-unit-ruby-core"
+gem "power_assert", "~> 2.0" if RUBY_VERSION < '3.1' # https://github.com/ruby/power_assert/pull/61
 gem "webrick"
