Use testCompile for kotlin test to help Gradle find tests

Author: rdbatch

build.gradle.kts

@@ -20,8 +20,8 @@ dependencies {
     compile(group = "org.http4k", name = "http4k-server-apache", version = http4kVersion)
     compile(group = "org.http4k", name = "http4k-format-jackson", version = http4kVersion)
 
-    testImplementation(kotlin("test"))
-    testImplementation(kotlin("test-junit"))
+    testCompile(kotlin("test"))
+    testCompile(kotlin("test-junit"))
     testImplementation("io.mockk:mockk:1.9.3")
     testCompile(group = "org.http4k", name = "http4k-testing-hamkrest", version = http4kVersion)
 }