Cap root json for TruffleRuby CI

pboling · pboling · commit 5705efbb0dea · 2026-06-03T10:25:38.000-06:00
diff --git a/Appraisal.root.gemfile b/Appraisal.root.gemfile
@@ -14,3 +14,7 @@ source "https://gem.coop"
 # We do not load the standard Gemfile, as it is tailored for local development.
 
 gemspec
+
+if defined?(RUBY_ENGINE) && RUBY_ENGINE == "truffleruby"
+  gem "json", "< 2.18"
+end
