Update dependency io.undertow:undertow-core to v2.3.21.Final [SECURITY]

Author: renovate[bot]

pom.xml

@@ -11,7 +11,7 @@
 	<properties>
 		<pac4j.version>6.3.3</pac4j.version>
 		<undertow-pac4j.version>6.0.1</undertow-pac4j.version>
-		<undertow.version>2.3.20.Final</undertow.version>
+		<undertow.version>2.3.21.Final</undertow.version>
 		<java.version>17</java.version>
 		<lombok.version>1.18.44</lombok.version>
 	</properties>