(PUP-11935) Update JRuby in tests to 9.3.y.z

Puppetserver upgraded from the JRuby 9.2.y.z series to JRuby 9.3.y.z as
part of SERVER-3133. This commit updates the JRuby version used in Rspec
tests to match the most recent JRuby version used in the Puppetserver
7.x series.

Author: mhashizume

.github/workflows/rspec_tests.yaml

@@ -20,7 +20,7 @@ jobs:
           - {os: ubuntu-latest, ruby: '2.6'}
           - {os: ubuntu-latest, ruby: '2.7'}
           - {os: ubuntu-latest, ruby: '3.0'}
-          - {os: ubuntu-latest, ruby: 'jruby-9.2.21.0'}
+          - {os: ubuntu-latest, ruby: 'jruby-9.3.9.0'}
           - {os: windows-2019, ruby: '2.5'}
           - {os: windows-2019, ruby: '2.6'}
           - {os: windows-2019, ruby: '2.7'}