finagle: Update scrooge-sbt-plugin version to 4.7.0

Problem

The scrooge-sbt-plugin version should be updated to 4.7.0 for release

Solution

Update the version.

RB_ID=826940
TBR=true

project/plugins.sbt

@@ -2,7 +2,7 @@ resolvers += Classpaths.sbtPluginReleases
 resolvers += "twitter-repo" at "https://maven.twttr.com"
 
 val branch = Process("git" :: "rev-parse" :: "--abbrev-ref" :: "HEAD" :: Nil).!!.trim
-val scroogeSbtPluginVersionPrefix = "4.6.0"
+val scroogeSbtPluginVersionPrefix = "4.7.0"
 val scroogeSbtPluginVersion =
   if (branch == "master") scroogeSbtPluginVersionPrefix
   else scroogeSbtPluginVersionPrefix + "-SNAPSHOT"