SLING-7398 - Run the Sling ITs with Java 10

Activate Java 8 build.
diff --git a/.sling-module.xml b/.sling-module.xml
index 698e881..68b1402 100644
--- a/.sling-module.xml
+++ b/.sling-module.xml
@@ -22,6 +22,7 @@
         <jdks>
             <jdk>1.8</jdk>
             <jdk>9</jdk>
+            <jdk>10</jdk>
         </jdks>
         <archivePatterns>
             <archivePattern>**/logs/*.log</archivePattern>