properly target java 1.8

Author: hauner

build.gradle.kts

@@ -9,6 +9,10 @@ plugins {
 group = "com.github.hauner.openapi"
 version = "1.0.0.M3"
 
+tasks.compileKotlin {
+    kotlinOptions.jvmTarget = "1.8"
+}
+
 repositories {
     mavenCentral()
     maven {
@@ -24,8 +28,7 @@ project.ext {
 }
 
 dependencies {
-//    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
-    implementation(kotlin("stdlib"))
+    implementation(kotlin("stdlib-jdk8"))
 
     implementation("io.swagger.parser.v3:swagger-parser:2.0.19") {
         exclude(group = "io.swagger.parser.v3", module = "swagger-parser-v2-converter")