Update dependency org.apache.maven:maven-plugin-api to v3.9.9

Author: renovate[bot]

cxf-spring-boot-starter-maven-plugin/pom.xml

@@ -41,7 +41,7 @@
 		<mojo-executor.version>2.3.1</mojo-executor.version>
 		<maven-plugin-plugin.version>3.15.1</maven-plugin-plugin.version>
 		<maven-plugin-annotations.version>3.15.1</maven-plugin-annotations.version>
-		<maven-plugin-api.version>3.6.3</maven-plugin-api.version>
+		<maven-plugin-api.version>3.9.9</maven-plugin-api.version>
 
 		<!-- Testing dependencies -->
 		<junit.version>5.12.0</junit.version>