Update vertx version to 4.5.21 (#578)

Author: cYKatherine

pom.xml

@@ -10,7 +10,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <vertx.version>4.5.18</vertx.version>
+        <vertx.version>4.5.21</vertx.version>
         <vertx-maven-plugin.version>1.0.22</vertx-maven-plugin.version>
         <vertx.verticle>com.uid2.admin.vertx.AdminVerticle</vertx.verticle>
         <!-- check micrometer.version vertx-micrometer-metrics consumes before bumping up -->