Add UTC timezone to xml

[Xpirix]

• This is a fix for #353

Changes summary

• Update local_timezone filter to return directly utcdate
• Apply the filter to the created date and updated date

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (998e0b5) 36.06% compared to head (50f2585) 36.06%.

:exclamation: Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #360 +/- ## ======================================= Coverage 36.06% 36.06% ======================================= Files 111 111 Lines 4899 4899 ======================================= Hits 1767 1767 Misses 3132 3132 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[pathmapper]

Thanks, so the list delivers always these dates in UTC, right?

[Xpirix]

@pathmapper My pleasure.

so the list delivers always these dates in UTC, right?

Yes, I just added the timezone to be more precise. I was also thinking about a format with the user timezone like in the plugin details but I wonder if it's acceptable by the plugin manager, it also involves using javascript and could change the inner content by adding another tag.

[pathmapper]

I think UTC is fine and the plugin manager should handle to display local timezones if wanted.

[dimasciput]

@Xpirix could you test this on the qgis too

[Xpirix]

@dimasciput Sure, I've tested on QGIS and successfully retrieved my test plugin with UTC datetime.

In the xml list:

In the plugin manager:

[pathmapper]

Plugin manager now shows the update_date in local time -> https://github.com/qgis/QGIS/pull/56530