Merge pull request #294 from http4s/update/series/0.24/jetty-server-10.0.21

Update jetty-client, jetty-runner, ... to 10.0.21 in series/0.24

Author: rossabaker

build.sbt

@@ -21,7 +21,7 @@ ThisBuild / tlJdkRelease := Some(8)
 lazy val root = tlCrossRootProject.aggregate(servlet, examples)
 
 val asyncHttpClientVersion = "2.12.3"
-val jettyVersion = "10.0.15"
+val jettyVersion = "10.0.21"
 val http4sVersion = "0.23.27"
 val munitCatsEffectVersion = "1.0.7"
 val servletApiVersion = "4.0.1"