cmd/ursrv: Attempt to fix js failure to load (#6747)

Following what was said in:

https://support.google.com/maps/thread/44057943?hl=en

cmd/ursrv/static/index.html

@@ -40,13 +40,13 @@ found in the LICENSE file.
     }
   </style>
   <script type="text/javascript"
-          src="https://www.google.com/jsapi?autoload={
-            'modules':[{
-              'name':'visualization',
-              'version':'1',
-              'packages':['corechart']
+          src='https://www.google.com/jsapi?autoload={
+            "modules":[{
+              "name":"visualization",
+              "version":"1",
+              "packages":["corechart"]
             }]
-          }"></script>
+          }'></script>
 
   <script type="text/javascript">
     google.setOnLoadCallback(drawVersionChart);