Android: Fix return type of ISO

Returning an array is inconsistent with IOS and also gives some numbers that can't even be easily converted to the 'real' ISO you just get back automatically when this field is a string.

Author: IsaacInsoll

android/src/main/java/com/lodev09/exify/ExifyTags.kt

@@ -68,7 +68,7 @@ val EXIFY_TAGS = arrayOf(
   arrayOf("double", ExifInterface.TAG_FOCAL_PLANE_X_RESOLUTION),
   arrayOf("double", ExifInterface.TAG_FOCAL_PLANE_Y_RESOLUTION),
   arrayOf("int", ExifInterface.TAG_GAIN_CONTROL),
-  arrayOf("array", ExifInterface.TAG_ISO_SPEED_RATINGS),
+  arrayOf("string", ExifInterface.TAG_ISO_SPEED_RATINGS),
   arrayOf("string", ExifInterface.TAG_IMAGE_UNIQUE_ID),
   arrayOf("int", ExifInterface.TAG_LIGHT_SOURCE),
   arrayOf("string", ExifInterface.TAG_MAKER_NOTE),