SLING-2938 - build fails with jdk 11, restrict to 8 for now

.sling-module.json

diff --git a/.sling-module.json b/.sling-module.json
new file mode 100644
index 0000000..cbc4549
--- /dev/null
+++ b/.sling-module.json
@@ -0,0 +1,5 @@
+{
+  "jenkins":{
+    "jdks": [8]
+  }
+}