Editing a post on Akkoma instance throws up incorrect error about polls

**Describe the bug**
Trying to edit a post on social.rjp.is (an Akkoma instance) gives "poll - Invalid object. Got: boolean." even though the post doesn't have a poll.

Testing a theory by hand triggers this error if the request has `"poll": false` (which is an invalid request according to my reading of https://docs.joinmastodon.org/methods/statuses/#edit anyway.)

```
{
"error": "poll - Invalid object. Got: boolean.",
"errors": [
{
"message": "Invalid object. Got: boolean",
"source": {
"pointer": "/poll"
},
"title": "Invalid value"
}
]
}
```

Probably best to not send any fields if they're not being specifically updated in the update call?

**To Reproduce**
1. Post using an Akkoma (probably also a Pleroma) instance
2. Edit the post
3. Hit "Update"

**Expected behavior**
The post should be updated.

**Screenshots**

**Desktop**
- OS: macOS Sonoma 14.4 (23E214)
- Browser: Safari 17.4 (19618.1.15.11.12)
- Version: Phanpy 2024.03.17.c7c764a (self-hosting)

Start by reproducing post editing on an Akkoma instance and inspect the update request sent when the post has no poll. Compare it with the Mastodon edit-statuses API requirements, then verify that editing succeeds without sending an invalid poll value.

Written by the indexing model from the issue text.