Two strings in pmpro-gift-levels.php can now be localized

[DAnn2012]

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Changes proposed in this Pull Request:

Two strings in pmpro-gift-levels.php can now be localized

Changelog entry

Two strings in pmpro-gift-levels.php can now be localized

[DAnn2012]

Hello @andrewlimaza

Please could you take a look at this PR of mine?

Thanks.