Fix Android arbitrary date string parsing

[mabdurrahman]

Thanks for your great fork, I have been using it in production for a while and it works great, however, I hit an issue with one of my app's customers who is using an Android device because of a non-standard arbitrary birthday string in one of his contacts and I was able to reproduce the same issue using the example app.

I understand that the library has been migrated already to flexidate plugin for better date parsing, however, the issue is still reproducible, please check the steps to reproduce below for more details.

Steps to reproduce:

1. Use an Android device with their contacts synced to Google Contacts
2. Opened one of the synced contacts via Google Contacts web UI (https://contacts.google.com/)
3. Edit the contact
4. Show more fields
5. Add a non-standard arbitrary birthday string (i.e. 7 July 1960)
6. Wait for the contact to be synced back to the mobile device
7. Open the example app

Expected:

• Device contacts are loaded after sometime

Actual:

• The example app keeps loading indefinitely and the following PlatformException is thrown in the console:

  [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: PlatformException(unknown, java.lang.NumberFormatException: For input string: "7 July 1960", java.lang.NumberFormatException: For input string: "7 July 1960", null)
  #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:597:7)
  #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:158:18)
  <asynchronous suspension>
  #2      _defaultPageGenerator.<anonymous closure> (package:flutter_contact/base_contacts.dart:90:25)
  <asynchronous suspension>
  #3      _PeopleListPageState.refreshContacts (package:flutter_contact_example/people_list_page.dart:70:14)
  <asynchronous suspension>

[ericmartineau]

Thanks for this catch. I ended up handling this slightly differently, but the change will be present in the next release