Bump version to 3.1.1-SNAPSHOT.

Change-Id: I2f31564c39e8281ad53080199c12d9cb348e2089
diff --git a/pom.xml b/pom.xml
index 44868f1..d785cfc 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
   <modelVersion>4.0.0</modelVersion>
 
   <groupId>eu.mulk.quarkus-googlecloud-jsonlogging</groupId>
-  <version>3.1.0</version>
+  <version>3.1.1-SNAPSHOT</version>
 
   <artifactId>quarkus-googlecloud-jsonlogging-parent</artifactId>
   <packaging>pom</packaging>