Update dependency org.codehaus.mojo:exec-maven-plugin to v3

Author: renovatebot-confluentinc[bot]

scalable-payment-processing/pom.xml

@@ -31,7 +31,7 @@
         <java.version>8</java.version>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <exec-maven-plugin.version>1.2.1</exec-maven-plugin.version>
+        <exec-maven-plugin.version>3.5.0</exec-maven-plugin.version>
         <kafka.scala.version>2.11</kafka.scala.version>
         <kafka.version>2.3.0</kafka.version>
         <jersey.version>2.27</jersey.version>