Updated issue template example reproduction link (schrodinger#318)

Author: hoshmn

.github/ISSUE_TEMPLATE.md

@@ -14,7 +14,7 @@
 
 ## Steps to Reproduce (for bugs)
 <!--- Provide a link to a live example, or - -->
-<!--- Fork the jsfiddle to reproduce https://jsfiddle.net/uq8osbp1/ ->
+<!--- Fork the jsfiddle to reproduce https://codepen.io/alphalpha/pen/oqKJgG ->
 
 ## Context
 <!--- How has this issue affected you? What are you trying to accomplish? -->