[skip ci] Update Scala versions in readme

Author: cb372

docs/README.md

@@ -94,7 +94,7 @@ The plugin is published for the following Scala versions:
 
 * 2.11.12
 * 2.12.{8, 9, 10, 11}
-* 2.13.{0, 1}
+* 2.13.{0, 1, 2, 3}
 
 ## Changing the log level