Update Finagle to 19.4 (#4678)

frameworks/Scala/finagle/build.sbt

@@ -1,4 +1,4 @@
-lazy val finagleVersion = "19.3.0"
+lazy val finagleVersion = "19.4.0"
 
 name := "finagle-benchmark"
 scalaVersion := "2.12.5"

frameworks/Scala/finatra/build.sbt

@@ -1,4 +1,4 @@
-lazy val finatraVersion = "19.3.0"
+lazy val finatraVersion = "19.4.0"
 
 name := "techempower-benchmarks-finatra"
 organization := "com.twitter"