Update Kotlin sample to Spring Boot 3.5.0

This updates the grpc-server-kotlin-sample to Spring Boot
3.5.0 as it was missed in the previous commit.

Signed-off-by: Mingyuan Wu <my.wu@outlook.com>

samples/grpc-server-kotlin/pom.xml

@@ -6,7 +6,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>3.4.5</version>
+		<version>3.5.0</version>
 		<relativePath /> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>org.springframework.grpc</groupId>