[SnapdragonGallery] Change target SDK to 28.

Change-Id: Ibb3063842be23538390544c4e0a29cfbccf3ea9c
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index e67eefa..64ace8e 100755
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -24,7 +24,7 @@
 
     <original-package android:name="com.android.gallery3d" />
 
-    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="26"/>
+    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="28"/>
 
     <permission android:name="com.android.gallery3d.permission.GALLERY_PROVIDER"
                 android:protectionLevel="signatureOrSystem" />