bump to 20.9.0 (#6056)

frameworks/Scala/finagle/build.sbt

@@ -1,4 +1,4 @@
-lazy val finagleVersion = "20.8.1"
+lazy val finagleVersion = "20.9.0"
 
 name := "finagle-benchmark"
 scalaVersion := "2.12.8"

frameworks/Scala/finatra/build.sbt

@@ -1,4 +1,4 @@
-lazy val finatraVersion = "20.8.1"
+lazy val finatraVersion = "20.9.0"
 
 name := "techempower-benchmarks-finatra"
 organization := "com.twitter"