manifest: Add permission to read external storage

This fixes support for file managers that don't proxy the file access
from the file selection dialog through a content provider, and just
return a raw file:// URL. In this case, resolver.openInputStream() tries
to open the file directly, and fails with "Permission denied".

Signed-off-by: Samuel Holland <samuel@sholland.org>

app/src/main/AndroidManifest.xml

@@ -5,6 +5,7 @@
     android:installLocation="internalOnly">
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
 
     <application