Fix 2081: Replace serde_yaml::to_string with serde_json::to_string_yaml

[hesampakdaman]

Closes #2081.

The output will look a bit uglier, but it does the job. Here's my machine

{
  "atuin": {
    "version": "18.2.0",
    "sync": null,
    "sqlite_version": "3.44.0"
  },
  "shell": {
    "name": "bash",
    "default": "bash",
    "plugins": [],
    "preexec": null
  },
  "system": {
    "os": "Ubuntu",
    "arch": "x86_64",
    "version": "23.10",
    "disks": [
      {
        "name": "/dev/sda2",
        "filesystem": "ext4"
      },
      {
        "name": "/dev/sdb1",
        "filesystem": "ext4"
      },
      {
        "name": "/dev/sda2",
        "filesystem": "ext4"
      }
    ]
  }
}

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[ellie]

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