tests/models: use d.copy() instead of dict(d)

for better clarity on the code author's intention.

Test Plan

Depends on !90 (closed).

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Migrated from D2816 (view on Phabricator)

Build is green See https://jenkins.softwareheritage.org/job/DMOD/job/tox/211/ for more details.

mentioned in merge request !92 (closed)

Merge request was accepted

approved this merge request

Merge request was merged

closed