Post-release of v0.1.2 by @andrew-nowak: set snapshot version

Setting snapshot version after @andrew-nowak published https://github.com/guardian/kcl-pekko-stream/releases/tag/v0.1.2

Author: gu-scala-library-release[bot]

version.sbt

@@ -1 +1 @@
-ThisBuild / version := "0.1.2"
+ThisBuild / version := "0.1.3-SNAPSHOT"