android: Update mainfiest and build.grade for target SDK version 29.

src/android/app/build.gradle

@@ -31,7 +31,7 @@ android {
         // TODO If this is ever modified, change application_id in strings.xml
         applicationId "org.citra.citra_emu"
         minSdkVersion 26
-        targetSdkVersion 28
+        targetSdkVersion 29
         versionCode autoVersion
         versionName getVersion()
         ndk.abiFilters abiFilter

src/android/app/src/main/AndroidManifest.xml

@@ -28,7 +28,8 @@
         android:allowBackup="false"
         android:supportsRtl="true"
         android:isGame="true"
-        android:banner="@mipmap/ic_launcher">
+        android:banner="@mipmap/ic_launcher"
+        android:requestLegacyExternalStorage="true">
 
         <activity
             android:name="org.citra.citra_emu.ui.main.MainActivity"

src/android/build.gradle

@@ -7,7 +7,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.0.0'
+        classpath 'com.android.tools.build:gradle:4.0.1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files