update required for the version of the Android embedding.

[sachin-dahal]

While running the project, flutter warns that flutter_pdfview uses a deprecated version of the Android embedding.

The plugins flutter_pdfview use a deprecated version of the Android embedding.
To avoid unexpected runtime failures or future build failures, try to see if these plugins support the Android V2 embedding. Otherwise, consider removing them since a future release of Flutter will remove these deprecated APIs.

If you are a plugin author, take a look at the docs for migrating the plugin to the V2 embedding: https://flutter.dev/go/android-plugin-migration.