Update sbt to 1.6.0 (#578)

scala-steward · web-flow · commit 4445b4d54836 · 2021-12-26T21:52:45.000-08:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.5.8
+sbt.version=1.6.0
