update streams version in readme

README.md

@@ -31,7 +31,7 @@ res0: Option[Country] = Some(Country(FRA,France,59225700))
 The current release is **0.2.3**, which works on Scala **2.10.5** and **2.11** with
 
 - scalaz 7.1
-- scalaz-stream 0.7.1a
+- scalaz-stream 0.7.2a
 - shapeless 2.2.2
 
 You should expect minor breaking changes for at least the next few versions, although these will be documented and kept to a minimum. To use **doobie** you need to add the following to your `build.sbt`.