Library uses the pre-2017 flag of Mauritania

[stoberov]

Describe the bug
In 2017, Mauritania changed its flag to include a top and bottom red color.
Link to Wikipedia = https://en.wikipedia.org/wiki/Mauritania#/media/File:Flag_of_Mauritania.svg

The FlagPhoneNumber is using the old flag.

To Reproduce
Steps to reproduce the behavior:

1. Choose Mauritania
2. The flag is green. No red.

Expected behavior
A red-green-red flag.

Screenshots

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