README: removed "download" stats badge

it's not working for a long time

Author: unclechu

README.md

@@ -7,8 +7,6 @@ Recursive object extending.
 
 [![NPM](https://nodei.co/npm/deep-extend.png?downloads=true&downloadRank=true&stars=true)](https://nodei.co/npm/deep-extend/)
 
-[![NPM](https://nodei.co/npm-dl/deep-extend.png?height=3)](https://nodei.co/npm/deep-extend/)
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 Install
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