fix(tree): [tree] fix tree showLine props's bug , sometimes the line is too… (#2015)

* fix(tree): fix tree showLine props's bug ,  sometimes the line is too long

* fix(theme): update version

Author: shenjunjian

packages/theme/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@opentiny/vue-theme",
-  "version": "3.18.0",
+  "version": "3.18.1",
   "description": "An enterprise-class UI component library, support both Vue.js 2 and Vue.js 3, as well as PC and mobile.",
   "author": "OpenTiny Team",
   "license": "MIT",
@@ -87,4 +87,4 @@
       ]
     }
   }
-}
+}

packages/theme/src/tree/index.less

@@ -214,13 +214,12 @@
     .@{tree-node-prefix-cls}__children {
       overflow: visible !important;
       transition: 0.3s opacity ease-in-out;
+      position: relative;
 
       &
         .@{tree-node-prefix-cls}__wrapper:not(:last-child)
         > .@{tree-node-prefix-cls}
         > .@{tree-node-prefix-cls}__children {
-        position: relative;
-
         .@{tree-node-prefix-cls}__children-indent {
           height: 100%;
           position: absolute;