fix link

Author: AdarShaked

plugin.yaml

@@ -1,7 +1,7 @@
 plugins:
   diamond:
     executor: host_agent
-    source: https://github.com/cloudify-cosmo/cloudify-diamond-plugin/archive/1.3.18.zip
+    source: https://github.com/cloudify-cosmo/cloudify-diamond-plugin/archive/1.3.19.zip
     package_name: cloudify-diamond-plugin
     package_version: '1.3.19'
     install: false