升级element-ui到最新版本2.15.6

ruoyi-ui/package.json

@@ -41,7 +41,7 @@
     "clipboard": "2.0.6",
     "core-js": "3.8.1",
     "echarts": "4.9.0",
-    "element-ui": "2.15.5",
+    "element-ui": "2.15.6",
     "file-saver": "2.0.5",
     "fuse.js": "6.4.3",
     "highlight.js": "9.18.5",