Update scalatest to 3.2.0 (#203)

Author: scala-steward

build.sbt

@@ -21,7 +21,7 @@ lazy val exercises = (project in file("."))
       "org.scala-exercises"        %% "exercise-compiler"         % "0.6.1",
       "org.scala-exercises"        %% "definitions"               % "0.6.1",
       "com.chuusai"                %% "shapeless"                 % "2.3.3",
-      "org.scalatest"              %% "scalatest"                 % "3.1.2",
+      "org.scalatest"              %% "scalatest"                 % "3.2.0",
       "org.scalacheck"             %% "scalacheck"                % "1.14.3",
       "org.scalatestplus"          %% "scalacheck-1-14"           % "3.1.2.0",
       "com.github.alexarchambault" %% "scalacheck-shapeless_1.14" % "1.2.5"