build: Bump version to 6.6.1-SNAPSHOT.

Change-Id: I48b8eeb21baa6fed22e831405fee716e35c0b3bf
diff --git a/core/pom.xml b/core/pom.xml
index 744da0e..7320b24 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>6.6.0</version>
+    <version>6.6.1-SNAPSHOT</version>
   </parent>
 
   <artifactId>quarkus-googlecloud-jsonlogging-core</artifactId>