Add version to JaCoCo plugin in pom.xml

The JaCoCo Maven plugin was missing the required version element.
Added version 0.8.13 with proper version tracking comment format.

Author: Changjian Wang

sdk/contentunderstanding/azure-ai-contentunderstanding/pom.xml

@@ -80,6 +80,7 @@
       <plugin>
         <groupId>org.jacoco</groupId>
         <artifactId>jacoco-maven-plugin</artifactId>
+        <version>0.8.13</version> <!-- {x-version-update;org.jacoco:jacoco-maven-plugin;external_dependency} -->
         <configuration>
           <excludes>
             <exclude>${jacoco.maven.plugin.excludes}</exclude>