timewarp pull-exif timezone fails to update Photos Timezone info when offset_seconds == 0

[oPromessa]

Before submitting a bug report, please ensure you are running the most recent version of osxphotos and that the bug is reproducible on the latest version

osxphotos --version
osxphotos, version 0.68.6
Python 3.11.5 (main, Aug 24 2023, 15:23:30) [Clang 14.0.0 (clang-1400.0.29.202)]
macOS 12.7.6, x86_64

Describe the bug

When EXIF based offset is 0 (in the case of GTM timezone), the date time gets pulled from the file EXIF into Photos database but not the offset/timezone.

I believe issue would be here: when `dtinfo.offset_seconds is valid (not None) and equals 0 for GMT offset, this test fails

osxphotos/osxphotos/exif_datetime_updater.py

Line 181 in 808095c

if dtinfo.offset_seconds:

I believe it should be:

    if dtinfo.offset_seconds is not None:

To Reproduce

$ exiftool -a -G1 -s -api QuickTimeUTC=1 -time:all -api RequestAll=2 -*offset* file.JPG
[ExifTool]      Now                             : 2024:10:07 17:26:58+01:00
(...)
[ExifIFD]       DateTimeOriginal                : 2019:07:21 23:37:38
[ExifIFD]       CreateDate                      : 2019:07:21 23:37:38
[ExifIFD]       OffsetTime                      : +00:00
[ExifIFD]       OffsetTimeOriginal              : +00:00
[ExifIFD]       OffsetTimeDigitized             : +00:00
(...)
[Composite]     SubSecCreateDate                : 2019:07:21 23:37:38+00:00
[Composite]     SubSecDateTimeOriginal          : 2019:07:21 23:37:38+00:00
[Composite]     SubSecModifyDate                : 2019:07:21 23:37:38+00:00
[Composite]     GPSDateTime                     : 2019:07:21 23:37:38Z
[Composite]     DateTimeCreated                 : 2019:07:21 23:37:38+00:00
[Composite]     DigitalCreationDateTime         : 2019:07:21 23:37:38+00:00
[ExifIFD]       OffsetTime                      : +00:00
[ExifIFD]       OffsetTimeOriginal              : +00:00
[ExifIFD]       OffsetTimeDigitized             : +00:00

$ osxphotos timewarp -c
filename, uuid, photo time (Photos), photo time (EXIF), timezone offset (Photos), timezone offset (EXIF)
file.JPG, A7D2E1C0-2DEB-4B72-8BB1-98749EC6C44C, 2019-07-22 01:37:38, 2019-07-21 23:37:38, +0200, +0000

$ osxphotos timewarp --pull-exif --verbose 
exiftool path: /usr/local/bin/exiftool
⚠️  About to process 1 photo with timewarp. This will directly modify your 
Photos library database using undocumented features. While this functionality 
has been well tested, it is possible this may corrupt, damage, or destroy your
Photos library. Use at your own caution. No warranty is implied or provided. 
It is strongly recommended you make a backup of your Photos library before 
using the timewarp command (for example, using Time Machine).

Proceed with timewarp? [y/N]: y
Updating Photos from EXIF data for file.JPG (A7D2E1C0-2DEB-4B72-8BB1-98749EC6C44C)
Updated date/time for photo file.JPG (A7D2E1C0-2DEB-4B72-8BB1-98749EC6C44C): 2019-07-22 00:37:38
Done.

• Side Note: The date time indicated by pull-exif is 2019-07-22 00:37:38 (localised as per the following code line) and not 2019:07:21 23:37:38 as per EXIF data.
  

  osxphotos/osxphotos/exif_datetime_updater.py

  Line 196 in 808095c

  local_datetime = datetime_remove_tz(

Expected behavior
Consider the offset == 0 case.

Screenshots
N/A
Desktop (please complete the following information):

osxphotos --version
osxphotos, version 0.68.6
Python 3.11.5 (main, Aug 24 2023, 15:23:30) [Clang 14.0.0 (clang-1400.0.29.202)]
macOS 12.7.6, x86_64

Additional context
Working on a PR 😄 !