Update Readme.md to the most recent version of paper_trail: 0.8

README.md

@@ -104,7 +104,7 @@ The library source code is minimal and well tested. It is suggested to read the
 
   ```elixir
     def deps do
-      [{:paper_trail, "~> 0.7.3"}]
+      [{:paper_trail, "~> 0.8"}]
     end
   ```