Migrate fluent-en_GB SmokeTest from spek to kotest

Migrated the SmokeSpec file from Spek to Kotest using Descibe Spec.
Used Kotest version 4.2.3. In the latest Kotest Versions,
min kotlin version is limited to 1.6 but atrium uses kotlin 1.3.2.
Kotest 4.3.2 is the last version which is compatible with kotlin 1.3.x
Will have to bump these version once Kotlin version is updated here.

Resolves: robstoll#1202

bundles/fluent-en_GB/atrium-fluent-en_GB/build.gradle.kts

@@ -3,9 +3,6 @@ description = "Represents a convenience module which merely bundles dependencies
 val kotestVersion: String by rootProject.extra
 
 kotlin {
-    tasks.withType<Test> {
-        useJUnitPlatform()
-    }
     sourceSets {
         val commonMain by getting {
             dependencies {
@@ -24,7 +21,6 @@ kotlin {
         val commonTest by getting {
             dependencies {
                 implementation("io.kotest:kotest-runner-junit5:$kotestVersion") // for kotest framework
-                implementation("io.kotest:kotest-property:$kotestVersion") // for kotest property test
             }
         }
     }

bundles/fluent-en_GB/atrium-fluent-en_GB/src/jvmTest/kotlin/custom/SmokeSpec.kt

@@ -15,7 +15,7 @@ import ch.tutteli.atrium.translations.DescriptionBasic.TO_BE
 import io.kotest.core.spec.style.DescribeSpec
 import java.nio.file.Paths
 
-object SmokeSpec : DescribeSpec({
+class SmokeSpec : DescribeSpec({
     describe("Smoke Test") {
         it("see if `toEqual` can be used") {
             expect(1).toEqual(1)