Merge pull request #388 from scala-steward/update/http4s-server-0.21.0

Update http4s-blaze-server, http4s-dsl, ... to 0.21.0

Author: zarthross

Diff for: project/Dependencies.scala

@@ -2,7 +2,7 @@ import sbt._
 import Keys._
 
 object Dependencies {
-  lazy val http4sVersion = "0.21.0-RC5"
+  lazy val http4sVersion = "0.21.0"
   lazy val specs2Version = "4.8.1"
 
   lazy val http4sServer        = "org.http4s"                 %% "http4s-server"         % http4sVersion