Examples: Android: Update kotlin version (#8409)

examples/example_android_opengl3/android/app/build.gradle

@@ -42,5 +42,5 @@ repositories {
     mavenCentral()
 }
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 }