Update sbt-scoverage to 2.3.1

Author: scala-steward

project/plugins.sbt

@@ -1,7 +1,7 @@
 addSbtPlugin("pl.project13.scala" % "sbt-jmh"              % "0.4.3")
 addSbtPlugin("com.47deg"          % "sbt-microsites"       % "1.3.4")
 addSbtPlugin("org.scalameta"      % "sbt-scalafmt"         % "2.4.6")
-addSbtPlugin("org.scoverage"      % "sbt-scoverage"        % "1.9.3")
+addSbtPlugin("org.scoverage"      % "sbt-scoverage"        % "2.3.1")
 addSbtPlugin("org.scalameta"      % "sbt-mdoc"             % "2.2.24")
 addSbtPlugin("com.codecommit"     % "sbt-spiewak-sonatype" % "0.22.1")
 addSbtPlugin("com.github.sbt"     % "sbt-unidoc"           % "0.5.0")