Add jruby-10.0.5.0 to CI test matrix with Oracle JDK 21

Add jruby-10.0.5.0 to the `test` workflow matrix so the Oracle JDBC
code path is exercised on every push.

JRuby 10 targets Java 21 bytecode (class file version 65) and
Oracle's ojdbc17.jar is certified with JDK 17 and JDK 21, so install
Oracle JDK 21 explicitly via actions/setup-java for JRuby matrix
entries (scoped via `if: startsWith(matrix.ruby, 'jruby')`).
Picking Oracle JDK matches the distribution most users run in
production alongside the Oracle JDBC driver, and Oracle JDK 21 is
available at no cost under the NFTC license.

Author: yahonda

.github/workflows/test.yml

@@ -15,7 +15,8 @@ jobs:
           '4.0',
           '3.4',
           '3.3',
-          '3.2'
+          '3.2',
+          'jruby-10.0.5.0',
         ]
     env:
       ORACLE_HOME: /opt/oracle/instantclient_23_26
@@ -42,6 +43,12 @@ jobs:
 
     steps:
     - uses: actions/checkout@v6
+    - name: Set up Java
+      if: startsWith(matrix.ruby, 'jruby')
+      uses: actions/setup-java@v4
+      with:
+        distribution: oracle
+        java-version: '21'
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with: