Update dependency org.apache.maven.plugins:maven-source-plugin to v3.4.0

Author: xdev-renovate

vaadin-package-json-optimizer/pom.xml

@@ -187,7 +187,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-source-plugin</artifactId>
-				<version>3.3.1</version>
+				<version>3.4.0</version>
 				<executions>
 					<execution>
 						<id>attach-sources</id>