fix: date_time fields timezone

[Paul-Bob]

Description

Fixes #2510

Flatpickr is always using the local timezone when editing. If timezone option is present it will ignore it. With this PR we change the timezone of the selected input keeping the date and time values before converting it to UTC.

Force timezone option when UTC to Etc/UTC on edit due this issue moment/luxon#1358

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

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[github-actions]

This PR has been merged into main. The functionality will be available in the next release.

Please check the release guide for more information.