Update readme

README.md

@@ -11,7 +11,7 @@ The package can be installed by adding `ex_keccak` to your list of dependencies
 ```elixir
 def deps do
   [
-    {:ex_keccak, "~> 0.7.3"}
+    {:ex_keccak, "~> 0.7.4"}
   ]
 end
 ```