add index suffix to duplicated group names

lib/providers/dingtalk.js

@@ -107,6 +107,17 @@ async function fetchAllDepartments() {
     });
 
     allDeps = Object.values(depsMap);
+    const allDepNames = {};
+    allDeps.forEach(v => {
+      let name = v.name;
+      let idx = 2;
+      while (allDepNames[name]) {
+        name = v.name + idx;
+        idx++;
+      }
+      allDepNames[name] = 1;
+      v.name = name;
+    })
 
     saveCacheToFile('dingtalk_groups.json', allDeps);
   }