Fork test execution to contain metaspace

Before this change tests running on CI pipelines might have failed due to
java.lang.OutOfMemoryError: Metaspace

Change-Id: I1d0537ea4f07f6456167331a1ebbb239e2c7e99e
diff --git a/project/SharedSettings.scala b/project/SharedSettings.scala
index 7a6f5b2..3c05034 100644
--- a/project/SharedSettings.scala
+++ b/project/SharedSettings.scala
@@ -28,6 +28,7 @@
     scalaVersion := "2.11.8",
     organization := "gerritforge",
     parallelExecution in Test := false,
+    fork in Test := true,
     git.useGitDescribe := true,
     libraryDependencies ++= Seq(
       "org.apache.spark"           %% "spark-core"             % sparkVersion % "provided" exclude("org.spark-project.spark", "unused"),