Bump Finagle benchmarks to 19.3.0 (#4547)

* Finagle to 19.3.0

* Finatra to 19.3.0

frameworks/Scala/finagle/build.sbt

@@ -1,4 +1,4 @@
-lazy val finagleVersion = "19.2.0"
+lazy val finagleVersion = "19.3.0"
 
 name := "finagle-benchmark"
 scalaVersion := "2.12.5"

frameworks/Scala/finatra/build.sbt

@@ -1,4 +1,4 @@
-lazy val finatraVersion = "19.2.0"
+lazy val finatraVersion = "19.3.0"
 
 name := "techempower-benchmarks-finatra"
 organization := "com.twitter"