enable upgrade of sbt

Author: mkrzemien

.scala-steward.conf

@@ -1,6 +1,4 @@
 updates.ignore = [
-  {groupId = "com.softwaremill.sbt-softwaremill"},
-  {groupId = "org.scala-sbt"},
   {groupId = "org.scala-lang", artifactId = "scala-compiler", version = "2.12."},
   {groupId = "org.scala-lang", artifactId = "scala-compiler", version = "2.13."},
   {groupId = "org.scala-lang", artifactId = "scala-compiler", version = "3."}