build: Bump version to 6.3.1-SNAPSHOT.

Change-Id: Ifc3c9a1555f7533607557079cd2fbe767fa3ef02
diff --git a/core/pom.xml b/core/pom.xml
index 4a70b51..595cf38 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -14,7 +14,7 @@
   <parent>
     <groupId>eu.mulk.quarkus-googlecloud-jsonlogging</groupId>
     <artifactId>quarkus-googlecloud-jsonlogging-parent</artifactId>
-    <version>6.3.0</version>
+    <version>6.3.1-SNAPSHOT</version>
   </parent>
 
   <artifactId>quarkus-googlecloud-jsonlogging-core</artifactId>