Update sbt to 1.3.9

scala-steward · scala-steward · commit f66ea1907098 · 2020-03-31T20:15:37.000+02:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.8
+sbt.version=1.3.9
