Update dependency org.codehaus.mojo:exec-maven-plugin from v1.6.0 to v3

Author: renovate[bot]

gbfs-validator-java/pom.xml

@@ -58,7 +58,7 @@
 
         <jacoco-maven-plugin.version>0.8.13</jacoco-maven-plugin.version>
         <nexus-staging-maven-plugin.version>1.6.13</nexus-staging-maven-plugin.version>
-        <maven-exec-plugin.version>1.6.0</maven-exec-plugin.version>
+        <maven-exec-plugin.version>3.5.1</maven-exec-plugin.version>
         <maven-surefire-plugin.version>2.22.2</maven-surefire-plugin.version>
         <maven-enforcer-plugin.version>3.5.0</maven-enforcer-plugin.version>
         <maven-source-plugin.version>3.3.1</maven-source-plugin.version>