allow building on JDK 10 and 11

context/motivation: JDK 10 community build

Author: SethTisue

build.sbt

@@ -7,10 +7,14 @@ scalaVersionsByJvm in ThisBuild := {
   val v212 = "2.12.6"
   val v213 = "2.13.0-M3"
 
+  val allFalse = List(v212 -> false, v213 -> false, v211 -> false)
   Map(
     7 -> List(v211 -> false),
     8 -> List(v212 -> true, v213 -> true, v211 -> true),
-    9 -> List(v212 -> false, v213 -> false, v211 -> false))
+    9 -> allFalse,
+    10 -> allFalse,
+    11 -> allFalse
+  )
 }
 
 name := "scala-async"