Update ci.yml

.github/workflows/ci.yml

@@ -7,13 +7,13 @@ jobs:
     runs-on: ubuntu-18.04
     strategy:
       matrix:
-        ruby: [2.4, 2.7, 3.0]
+        ruby: [2.4, 2.7, 3.0, truffleruby-head]
 
     steps:
     - uses: actions/checkout@master
 
     - name: Sets up the Ruby version
-      uses: actions/setup-ruby@v1
+      uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}