Fix json bytes content type detection (#3941)
Fixes order of content type detection strategies for byte-encoded jsons.
Before
```
json_bytes = json.dumps([{"example": "data"}]).encode("utf-8")
file_buffer = io.BytesIO(json_bytes)
detect_filetype(file=file_buffer, metadata_file_path="filename.pdf")
```
Before
PDF
Now
JSON
