ruby.yml in snmp-open-0.8.0

- old
+ new

@@ -10,10 +10,18 @@
   test:
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        ruby: [2.4, 2.5, 2.6, 2.7, jruby]
+        ruby:
+        - '2.4'
+        - '2.5'
+        - '2.6'
+        - '2.7'
+        - '3.0'
+        - '3.1'
+        - jruby-9.2.21.0
+        - jruby-9.3.6.0
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
     - uses: ruby/setup-ruby@v1
       with: