chore(release): bump version to 6.16.8

- Update project version from 6.16.6 to 6.16.8 in gradle.properties
- Maintain existing project group and description unchanged
- Preserve website and issues URLs in properties file

Signed-off-by: Ahoo Wang <ahoowang@qq.com>

Author: Ahoo-Wang

gradle.properties

@@ -20,7 +20,7 @@ ksp.useKSP2=true
 ksp.incremental=true
 ksp.incremental.log=true
 group=me.ahoo.wow
-version=6.16.6
+version=6.16.8
 description=A Modern Reactive CQRS Architecture Microservice development framework based on DDD and EventSourcing.
 website=https://github.com/Ahoo-Wang/Wow
 issues=https://github.com/Ahoo-Wang/Wow/issues