Revert "Update sdk verison to 29"

This reverts commit 4eea939798e3c455ee1de09e9c5ae07cfd69befd.

Change-Id: I20fd3d62d38ddfbc323e8ff19c560d47659717b4
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 17999fb..60211c7 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="29"/>
+    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="28"/>
 
     <permission android:name="com.android.gallery3d.permission.GALLERY_PROVIDER"
                 android:protectionLevel="signatureOrSystem" />