In-app notification message content length change to 1024

https://dev.wormwood.com.sg/zentao/task-view-530.html

Strides-Admin/src/views/notification/add.vue

@@ -52,7 +52,7 @@
                 :autosize="autosize"
                 :readonly="!isEdit"
                 type="textarea"
-                maxlength="300"/>
+                maxlength="1000"/>
             </el-form-item>
           </el-col>
         </el-row>