Update sbt-scalafmt to 2.6.0 (#3)

Author: guizmaii

project/plugins.sbt

@@ -1,5 +1,5 @@
 addSbtPlugin("com.timushev.sbt" % "sbt-updates"    % "0.6.4")
-addSbtPlugin("org.scalameta"    % "sbt-scalafmt"   % "2.5.6")
+addSbtPlugin("org.scalameta"    % "sbt-scalafmt"   % "2.6.0")
 addSbtPlugin("org.scoverage"    % "sbt-scoverage"  % "2.4.4")
 addSbtPlugin("org.typelevel"    % "sbt-tpolecat"   % "0.5.3")
 addSbtPlugin("com.github.sbt"   % "sbt-ci-release" % "1.11.2")