Ensure Android Java and Kotlin compile to the same version

platform/android/java/lib/build.gradle

@@ -1,5 +1,7 @@
-apply plugin: 'com.android.library'
-apply plugin: 'kotlin-android'
+plugins {
+    id 'com.android.library'
+    id 'org.jetbrains.kotlin.android'
+}
 
 ext {
     PUBLISH_VERSION = getGodotPublishVersion()
@@ -34,6 +36,10 @@ android {
         targetCompatibility versions.javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = versions.javaVersion
+    }
+
     buildTypes {
         dev {
             initWith debug