Merge pull request #29 from jGleitz/java-8-compat

fix: set artefact compatibility to Java 8

Author: jGleitz

build.gradle.kts

@@ -1,4 +1,5 @@
 import de.marcphilipp.gradle.nexus.NexusRepository
+import org.gradle.api.JavaVersion.VERSION_1_8
 import org.jetbrains.dokka.gradle.DokkaTask
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
@@ -48,6 +49,11 @@ tasks.named<KotlinCompile>("compileTestKotlin") {
 	}
 }
 
+java {
+	sourceCompatibility = VERSION_1_8
+	targetCompatibility = VERSION_1_8
+}
+
 val sourcesJar by tasks.creating(Jar::class) {
 	group = "build"
 	description = "Assembles the source code into a jar"