When running `exiftool` against some files with non-ascii characters, we incur this error:
```
2023-01-16 11:04:38,734 ???? thumbor:ERROR UnicodeDecodeError: 'utf-8' codec can't decode byte 0x9c in position 19: invalid start byte
2023-01-16 11:04:38,734 ???? thumbor:ERROR ERROR: Traceback (most recent call last):
File "/opt/lib/python/site-packages/thumbor/handlers/__init__.py", line 212, in get_image
result = await self._fetch(self.context.request.image_url)
File "/opt/lib/python/site-packages/thumbor/handlers/__init__.py", line 876, in _fetch
raise fetch_result.exception
File "/opt/lib/python/site-packages/thumbor/handlers/__init__.py", line 844, in _fetch
self.context.request.engine.load(fetch_result.buffer, extension)
File "/srv/service/wikimedia_thumbor/engine/proxy/proxy.py", line 125, in load
self.lcl[enginename].load(buffer, extension)
File "/opt/lib/python/site-packages/thumbor/engines/__init__.py", line 195, in load
image_or_frames = self.create_image(buffer)
File "/srv/service/wikimedia_thumbor/engine/imagemagick/imagemagick.py", line 77, in create_image
self.read_exif(temp_file)
File "/srv/service/wikimedia_thumbor/engine/imagemagick/imagemagick.py", line 164, in read_exif
values = s.decode('utf-8').split(': ', 1)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x9c in position 19: invalid start byte
2023-01-16 11:04:38,734 ???? thumbor:ERROR [BaseHandler] get_image failed for url `https%3A//swift.discovery.wmnet/v1/AUTH_mw/wikipedia-commons-local-public.50/5/50/2023-01-15_15-49-13_voeux-maire-Belfort.jpg`. error: `'utf-8' codec can't decode byte 0x9c in position 19: invalid start byte`
2023-01-16 11:04:38,735 ???? tornado.access:ERROR 500 GET /wikipedia/commons/thumb/5/50/2023-01-15_15-49-13_voeux-maire-Belfort.jpg/1169px-2023-01-15_15-49-13_voeux-maire-Belfort.jpg (10.64.48.230) 4516.76ms
```
This occurs because the output of `exiftool` emits `Image Description : Vœux du Maire de Belfort, Damien Meslot, au gymnase Le Phare, Belfort, le 15 janvier 2023.`. "œ" is byte 0x9c
[[ https://upload.wikimedia.org/wikipedia/commons/thumb/5/50/2023-01-15_15-49-13_voeux-maire-Belfort.jpg/1169px-2023-01-15_15-49-13_voeux-maire-Belfort.jpg | This is the affected image ]]
[[ https://exiftool.org/forum/index.php?topic=12614.msg68199#msg68199 | According to the author of exiftool ]], unicode output isn't guaranteed unless JSON or XML output is used - we shouldn't be manually splitting string values in the first place, and this is another good reason to use JSON output everywhere.