Skip error on TruffleRuby

Author: nobu

.github/workflows/test.yml

@@ -43,6 +43,7 @@ jobs:
       run: bundle exec rake
       env:
         RUBYOPT: --enable-frozen_string_literal
+      continue-on-error: ${{ startsWith(matrix.ruby, 'truffle') }}
     - if: ${{ matrix.ruby == 'head' && startsWith(matrix.os, 'ubuntu') }}
       run: bundle exec rake rdoc
     - if: ${{ matrix.ruby == 'head' && startsWith(matrix.os, 'ubuntu') }}