Update scalatest to 3.2.20 (#515)

Author: scala-steward

project/Dependencies.scala

@@ -3,7 +3,7 @@ import sbt._
 object Version {
   val logback   = "1.4.14"
   val mockito   = "3.2.10.0"
-  val scalaTest = "3.2.19"
+  val scalaTest = "3.2.20"
   val slf4j     = "2.0.17"
 }