Update mockito-core to 5.21.0 (#611)

Author: scala-steward

build.sbt

@@ -11,7 +11,7 @@ lazy val commonSettings = Seq(
   crossVersion := CrossVersion.binary,
   libraryDependencies ++= Seq(
     "org.scalatest" %% "scalatest" % "3.2.19" % Test,
-    "org.mockito" % "mockito-core" % "5.20.0" % Test,
+    "org.mockito" % "mockito-core" % "5.21.0" % Test,
     "org.slf4j" % "slf4j-simple" % "2.0.17" % Test
   ),
   fork := true,