[3.0.x] sbt-scalafmt 2.6.0 (was 2.5.6) (#1296)

* [3.0.x] sbt-scalafmt 2.6.0 (was 2.5.6)

* update sbt

---------

Co-authored-by: Matthias Kurz <m.kurz@irregular.at>

Author: scala-steward

project/build.properties

@@ -1 +1 @@
-sbt.version=1.12.0
+sbt.version=1.12.9

project/plugins.sbt

@@ -20,6 +20,6 @@ addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.17")
 
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.3.2")
 
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.6")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.6.0")
 
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.11.2")