Update sbt to 1.3.13 (#71)

scala-steward · web-flow · commit 4655a7566804 · 2020-06-28T00:50:32.000Z
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.12
+sbt.version=1.3.13
