ruby.yml in blacklight-hierarchy-6.0.0

- old
+ new

@@ -16,10 +16,10 @@
 jobs:
   test:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: [2.7, 3.0]
+        ruby: [2.7, '3.0']
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with: