bump sbt version to 0.13.18

SethTisue · SethTisue · commit 525fd0ee212f · 2019-09-10T17:19:45.000-05:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=0.13.17
+sbt.version=0.13.18
