[BUG] upload dataset with 'keypoints' field to labelstudio correctly

[KirillSimonov]

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Describe the problem

The problem is the following:
Having fiftyone dataset with 'keypoints' field I am trying to use annotate() method to upload dataset to labelstudio. I attach screenshots. There is always only one point is uplaoded with coordinates (0, 0).
I did the same workflow for uploading fiftyone dataset with annotate() method for bbox objects and it works fine. However, i can not do the same for 'keypoints'.
I have not found similar issue and examples in repo on this topic so would be grateful to any assistance.
Thank you.

Code to reproduce issue

Provide a reproducible test case that is the bare minimum necessary to generate
the problem. Please avoid sharing code that relies on your local data or
datasets. Include a short video or screenshot if the bug is in the App.

![image](https://github.com/voxel51/fiftyone/assets/45141680/f23de188-c082-49c0-884b-84ce79f82592)
![image](https://github.com/voxel51/fiftyone/assets/45141680/df7adeb8-c1ad-4f48-9bc1-57ebb8632a92)
![image](https://github.com/voxel51/fiftyone/assets/45141680/ef4a7e70-d0d2-4174-949d-999ed808fa40)
![image](https://github.com/voxel51/fiftyone/assets/45141680/e520ece4-c9d5-451f-a01e-534899363635)

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 22.04): Windows 10 Enterprise
• Python version (python --version): Python 3.10.9
• FiftyOne version (fiftyone --version):
  - fiftyone 0.23.4
  fiftyone-brain 0.16.0
  fiftyone-db 0.4.0
  fiftyone-desktop 0.33.2
• FiftyOne installed from (pip):

Other info/logs

Versions of label-studio and tools:
label-studio 1.12.0
label-studio-converter 0.0.58
label-studio-sdk 0.0.32
label-studio-tools 0.0.3

Include any logs or source code that would be helpful to diagnose the problem.
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files should be attached. Please do not use screenshots for sharing text. Code
snippets should be used instead when providing tracebacks, logs, etc.

Willingness to contribute

The FiftyOne Community encourages bug fix contributions. Would you or another
member of your organization be willing to contribute a fix for this bug to the
FiftyOne codebase?

• Yes. I can contribute a fix for this bug independently
• Yes. I would be willing to contribute a fix for this bug with guidance
  from the FiftyOne community
• [x ] No. I cannot contribute a bug fix at this time