Update scalafmt-core to 2.6.0

Author: scala-steward

.scalafmt.conf

@@ -8,4 +8,4 @@ rewrite.rules = [ AvoidInfix, ExpandImportSelectors, RedundantParens, SortModifi
 rewrite.sortModifiers.order = [ "private", "protected", "final", "sealed", "abstract", "implicit", "override", "lazy" ]
 spaces.inImportCurlyBraces = true   # more idiomatic to include whitepsace in import x.{ yyy }
 trailingCommas = always
-version = 2.5.3
+version = 2.6.0