Update sbt, scripted-plugin to 1.12.0 (#321)

Co-authored-by: http4s-steward[bot] <106843772+http4s-steward[bot]@users.noreply.github.com>

Author: http4s-steward[bot]

project/build.properties

@@ -1 +1 @@
-sbt.version=1.11.7
+sbt.version=1.12.0