added rename endpoint for groups

src/services/group.js

@@ -37,6 +37,10 @@ class GroupService {
     async getUsersInGroup(groupId) {
         return (await db.query("SELECT id FROM users WHERE $1 = ANY(groups)", [groupId])).rows.map((group) => group.id)
     }
+
+    async rename(groupId, newName) {
+        await db.query("UPDATE groups SET name = $1 WHERE id = $2", [newName, groupId]).catch((e) => errorHandler(e, "groups"));;
+    }
 };
 
 export default new GroupService();