Ensure tests are run for all Ruby versions; add more Ruby versions

Author: geekq

.github/workflows/test.yml

@@ -4,15 +4,17 @@ on:
     branches:
       - develop
       - 1-2-stable
+      - 2-0-stable
   pull_request:
 jobs:
   test:
     name: Test
     runs-on: ubuntu-latest
     timeout-minutes: 15
     strategy:
+      fail-fast: false
       matrix:
-        ruby: [2.4, 2.7, 3.0]
+        ruby: [2.4, 2.5, 2.6, 2.7, 3.0, 3.1]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3