[FW][FIX] payment_payulatam: use url_root as base URL

[fw-bot]

Before this commit, the root URL of the request was not sent to PayuLatam, leading to redirection to an incorrect website when databases with a different domain were set. To use the url_root, get_base_url must be called from the payment.acquirer instance.

opw-3348291

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Forward-Port-Of: odoo/odoo#165092

[robodoo]

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[fw-bot]

This PR targets 16.0 and is part of the forward-port chain. Further PRs will be created up to master.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[fw-bot]

@pedrambiria ci/style failed on this forward-port PR

[fw-bot]

@pedrambiria ci/runbot failed on this forward-port PR

[fw-bot]

@pedrambiria this PR was modified / updated and has become a normal PR. It should be merged the normal way (via @robodoo)

[pedrambiria]

robodoo r+