Update build settings to use latest version of sbt and plugins

[xerial]

• Updated sbt and its plugins
• Fixed build.sbt to use slash syntaxes https://www.scala-sbt.org/1.x/docs/Migrating-from-sbt-013x.html#slash
• Upgraded sbt-sonatype to the latest version to have more stability for the release process.
• Code coverage test doesn't work well with Jacoco. We need another coverage solution

[xerial]

FYI: @komamitsu