text: Title: Request body is saved in a non human-readable format when it contains special characters
  Body: Hello and thank you for creating this tool, it looks very promising! The overall experience has been good so far, but I did notice an issue that's a bit inconvenient.
  
  I've created a `POST` request which contains letters with diacritics in the body, such as this one:
  
  ```json
  {
    "Hello": "There",
    "Hi": "Čau"
  }
  ```
  
  If I save the request into a yaml file, the body will be saved in a hard to read format:
  
  ```yaml
  name: Test
  method: POST
  url: https://example.org/test
  body:
    content: "{\n  \"Hello\": \"There\",\n  \"Hi\": \"\u010Cau\"\n}"
  ```
  
  If I replace the `Č` with a regular `C`, the resulting yaml file will have the format that I expect:
  
  ```yaml
  name: Test
  method: POST
  url: https://example.org/test
  body:
    content: |-
      {
        "Hello": "There",
        "Hi": "Cau"
      }
  ```
  
  Is it possible to fix this? The current behavior complicates manual editing and version control diffs, so I think it might be worth looking into.
  
  I'm using `posting` `1.7.0`
  
  Thanks!