Update dependency org.apache.maven.plugins:maven-javadoc-plugin to v3.8.0

Author: renovate[bot]

pom.xml

@@ -138,7 +138,7 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-javadoc-plugin</artifactId>
-					<version>3.1.1</version>
+					<version>3.8.0</version>
 				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
@@ -433,7 +433,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-javadoc-plugin</artifactId>
-				<version>3.1.1</version>
+				<version>3.8.0</version>
 				<configuration>
 					<excludePackageNames>ch.powerunit.extensions.async.impl*:ch.powerunit.extensions.async.impl</excludePackageNames>
 					<docfilessubdirs>true</docfilessubdirs>