Update sbt to 1.3.9 (#88)

scala-steward · web-flow · commit ac3925c944ce · 2020-03-31T11:21:16.000-07:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.8
+sbt.version=1.3.9
