Update compilerplugin, scalapb-runtime to 0.11.20

Author: scala-steward

project/plugins.sbt

@@ -18,7 +18,7 @@ addSbtPlugin("pl.project13.scala" % "sbt-jmh" % "0.4.7")
 addSbtPlugin("org.jetbrains" % "sbt-ide-settings" % "1.1.0")
 // testing protobufs
 addSbtPlugin("com.thesamet" % "sbt-protoc" % "1.0.8")
-libraryDependencies += "com.thesamet.scalapb" %% "compilerplugin" % "0.11.19"
+libraryDependencies += "com.thesamet.scalapb" %% "compilerplugin" % "0.11.20"
 // documentation
 addSbtPlugin("com.github.reibitto" % "sbt-welcome" % "0.5.0")