Tweak Scala compiler option

Author: takezoe

build.sbt

@@ -3,4 +3,4 @@ organization := "io.github.gitbucket"
 version := "1.10.0"
 scalaVersion := "2.13.3"
 gitbucketVersion := "4.35.0"
-scalacOptions := Seq("-deprecation", "-language:postfixOps", "-opt:l:method", "-feature")
+scalacOptions := Seq("-deprecation", "-language:postfixOps", "-feature")