Remove timezone workaround

[Aiz0]

Removing this will make FreeTube use the users timezone instead of defaulting to UTC.

closes FreeTubeApp/FreeTube#1429

This workaround was added in 279265a to prevent a crash.

I've tested and even using --env=TZ=ETC/Unknown does not cause any crashes.
running Intl.DateTimeFormat().resolvedOptions().timeZone returned Undefined
and new Date().ToLocaleString() returned '16/09/2022'

[flathubbot]

Started test build 110792

[flathubbot]

Build 110792 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/108415/io.freetubeapp.FreeTube.flatpakref

[flathubbot]

Started test build 59941

[flathubbot]

Build 59941 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/42579/io.freetubeapp.FreeTube.flatpakref

[PrestonN]

LGTM