Update slack.json

Suresh added slack mapping

Author: Suresh1346

slack.json

@@ -3983,6 +3983,10 @@
     {
       "github": "Asaleem-hmcts",
       "slack": "U08PVFLQV25"
+    },
+    {
+      "github": "Suresh1346",
+      "slack": "U08HZPHE7K8"
     }
   ]
 }