Fix problem on api 21

apng_library/src/main/java/oupson/apng/decoder/ApngDecoder.kt

@@ -76,7 +76,9 @@ class ApngDecoder {
                 val ihdr = IHDR()
                 var isApng = false
 
-                val drawable = AnimationDrawable()
+                val drawable = AnimationDrawable().apply {
+                    isOneShot = false
+                }
 
                 var buffer : Bitmap? = null
 

app-test/src/main/res/layout/fragment_apng_decoder.xml

@@ -5,7 +5,7 @@
         android:layout_height="match_parent"
         tools:context=".fragments.ApngDecoderFragment">
 
-    <ImageView
+    <androidx.appcompat.widget.AppCompatImageView
             android:id="@+id/apngDecoderImageView"
             android:layout_width="match_parent"
             android:layout_height="match_parent"

app-test/src/main/res/layout/fragment_java.xml

@@ -6,7 +6,7 @@
         xmlns:app="http://schemas.android.com/apk/res-auto"
         tools:context=".fragments.JavaFragment">
 
-    <ImageView
+    <androidx.appcompat.widget.AppCompatImageView
             android:id="@+id/javaImageView"
             android:layout_width="match_parent"
             android:layout_height="match_parent"