Update README.md

Author: ashleyfrieze

README.md

@@ -90,7 +90,7 @@ class WithEnvironmentVariables {
 <dependency>
   <groupId>uk.org.webcompere</groupId>
   <artifactId>system-stubs-junit4</artifactId>
-  <version>2.1.2</version>
+  <version>2.1.3</version>
 </dependency>
 ```