Re-add truffleruby-head in CI

* This reverts commit 5db4767.

Author: eregon

.github/workflows/test.yml

@@ -8,9 +8,7 @@ permissions:  # added using https://github.com/step-security/secure-workflows
 jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
-    with:
-      engine: cruby-jruby
-      versions: '["truffleruby"]'
+
   test:
     needs: ruby-versions
     strategy:
@@ -20,6 +18,8 @@ jobs:
         exclude:
           - os: windows-latest
             ruby: truffleruby
+          - os: windows-latest
+            ruby: truffleruby-head
           - os: windows-latest
             ruby: jruby
           - os: windows-latest