(PUP-11049) Enable ruby 3 rspec tests

Author: joshcooper

.github/workflows/rspec_tests.yaml

@@ -16,10 +16,12 @@ jobs:
           - {os: ubuntu-18.04, ruby: 2.5}
           - {os: ubuntu-18.04, ruby: 2.6}
           - {os: ubuntu-18.04, ruby: 2.7}
+          - {os: ubuntu-18.04, ruby: 3.0}
           - {os: ubuntu-18.04, ruby: jruby-9.2.9.0}
           - {os: windows-2016, ruby: 2.5}
           - {os: windows-2016, ruby: 2.6}
           - {os: windows-2016, ruby: 2.7}
+          - {os: windows-2016, ruby: 3.0}
 
     runs-on: ${{ matrix.cfg.os }}
     steps: