Update sbt to 1.3.9

scala-steward · scala-steward · commit 40ded673b66f · 2020-03-31T21:04:06.000+02:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.8
+sbt.version=1.3.9
