Update README.md

Author: AntyaDev

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <img src="https://github.com/PragmaticFlow/NBomber/blob/master/assets/nbomber_logo.png" alt="NBomber logo" width="600px">
+  <img src="https://github.com/PragmaticFlow/NBomber/blob/dev/assets/nbomber_logo.png" alt="NBomber logo" width="600px">
 </p>
 
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