ci.yml in stackprof-0.2.20

- old
+ new

@@ -6,10 +6,10 @@
   rubies:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ ruby-head, '3.0', '2.7', '2.6', '2.5', '2.4', '2.3', '2.2' ]
+        ruby: [ ruby-head, '3.1', '3.0', '2.7', '2.6', '2.5', '2.4', '2.3', '2.2' ]
     steps:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1