Bump io.undertow:undertow-core from 1.4.0.Final to 2.3.21.Final in /samples/server/petstore/undertow#4

dependabot[bot] wants to merge 1 commit intokube-clientappscodelabs/swagger-codegen:kube-clientfrom

dependabot/maven/samples/server/petstore/undertow/io.undertow-undertow-core-2.3.21.Finalappscodelabs/swagger-codegen:dependabot/maven/samples/server/petstore/undertow/io.undertow-undertow-core-2.3.21.FinalCopy head branch name to clipboard