[16.0][FIX] shopfloor_reception: fix expiration dates time zone handling

[nicolas-delbovier-acsone]

Following a first fix from: #1191

Reproduce the errors

• Create a db with shopfloor_reception and shopfloor_gs1 installed
• Make the tz of the warehouse's partner to something else than UTC

Error 1

Creating a lot from a GS1 scan does shift the time (e.g. you see "2026-12-31 01:00:00" in odoo instead of "2026-12-31 00:00:00")

Error 2

• Create a lot by hand for 2026-12-31 00:00:00" through odoo UI
• Scan the corresponding GS1 in the screen 'set_lot'
• You get the "Lot already exists, different expiration date" error tough you should not since the date do match

[OCA-git-bot]

Hi @mmequignon, @JuMiSanAr,
some modules you are maintaining are being modified, check this out!

[nicolas-delbovier-acsone]

@jbaudoux