Update rc-overflow to 1.2.8 (#531)

There are critical updates that need to be used.
https://github.com/react-component/overflow/commits/master

Author: simon-q

package.json

@@ -46,7 +46,7 @@
     "@babel/runtime": "^7.10.1",
     "classnames": "2.x",
     "rc-motion": "^2.4.3",
-    "rc-overflow": "^1.2.0",
+    "rc-overflow": "^1.2.8",
     "rc-trigger": "^5.1.2",
     "rc-util": "^5.12.0",
     "shallowequal": "^1.1.0"