Update README.md

Author: pjfanning

README.md

@@ -22,7 +22,7 @@ This is a fork of https://github.com/swagger-api/swagger-scala-module.
 To enable the swagger-scala-module, include the appropriate version in your project:
 
 ```
-  "com.github.swagger-akka-http" %% "swagger-scala-module" % "2.12.0"
+  "com.github.swagger-akka-http" %% "swagger-scala-module" % "2.13.0"
 ```
 
 ## How does it work?