[IMP] purchase_request: improved icon

[pedrocs-exo]

Now that creating Odoo icons is a snap, the purchase_request module icon could be improved and become more consistent with the other app icons. I can make a PR if the module maintainer so wishes.

[kittiu]

Would be nice. I think PR is a good separated module altogether.

[github-actions]

There hasn't been any activity on this issue in the past 6 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
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