Update sbt to 1.5.6 (#147)

scala-steward · web-flow · commit 172bfa3220ef · 2021-12-10T14:16:45.000-08:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.5.5
+sbt.version=1.5.6
