Revert JRuby update so build remains Java 17 compatible

spec/pom.xml

diff --git a/spec/pom.xml b/spec/pom.xml
index 64ea48b..765c5ad 100644
--- a/spec/pom.xml
+++ b/spec/pom.xml
@@ -84,7 +84,7 @@
         <maven.site.skip>true</maven.site.skip>
         <asciidoctorj.version>3.0.0</asciidoctorj.version>
         <asciidoctorj.pdf.version>2.3.21</asciidoctorj.pdf.version>
-        <jruby.version>10.0.2.0</jruby.version>
+        <jruby.version>9.4.14.0</jruby.version>
         <!-- status: DRAFT, BETA, etc., or blank for final -->
         <status>DRAFT</status>
         <maven.build.timestamp.format>MMMM dd, yyyy</maven.build.timestamp.format>