Remove Symmetry Investments logo (#474)

sure thing

Author: Geod24

README.md

@@ -88,6 +88,4 @@ void main()
 
 ### Our sponsors
 
-[<img src="https://raw.githubusercontent.com/libmir/mir-algorithm/master/images/symmetry.png" height="80" />](http://symmetryinvestments.com/) 	&nbsp; 	&nbsp;	&nbsp;	&nbsp;
 [<img src="https://raw.githubusercontent.com/libmir/mir-algorithm/master/images/kaleidic.jpeg" height="80" />](https://github.com/kaleidicassociates)
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