SLING-11161 Support testing with different JDKs

Also build with JDK 8 in Jenkins
diff --git a/.sling-module.json b/.sling-module.json
index 3f2b4e4..c4627e9 100644
--- a/.sling-module.json
+++ b/.sling-module.json
@@ -2,7 +2,8 @@
   "jenkins": {
     "jdks": [
       17,
-      11
+      11,
+      8
     ]
   }
 }