Update the gpt.js source to the Google supported version.

[garretthyder]

Update the gpt.js source to the Google supported version.

See https://developers.google.com/publisher-tag/guides/get-started

Received emals on usage of non-official URL due to this library;

Currently, your pages load gpt.js, pubads_impl.js, and/or other libraries are loading from a non-official URL. Before September 18th, 2023, you will need to update your <script> tag to load the GPT JavaScript from a Google domain following the guidance in our developers website.

Thank you

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