[GoPlay] Uses new API

[jeroenj]

Uses the new API (api.goplay.be) for the GoPlay extractor. The old API (api.viervijfzes.be) seems to have been shut down. The API domain now matches the extractor name as well (see #3412 for the initial rename).

Fixes #6032

Template

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• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

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[pukkandan]

I assume you have run the tests?

[jeroenj]

Yes, and tested manually with credentials (since the tests are skipped).