Removed extra trailing lf in multipart form fields

before patch:
```

-----------------------------mtynipxrmpegseog
Content-Disposition: form-data; name="width"
Content-Type: application/octet-stream

100

-----------------------------mtynipxrmpegseog
Content-Disposition: form-data; name="height"
Content-Type: application/octet-stream

80
-----------------------------mtynipxrmpegseog--
```
after patch:
```
-----------------------------mtynipxrmpegseog
Content-Disposition: form-data; name="width"
Content-Type: application/octet-stream

100
-----------------------------mtynipxrmpegseog
Content-Disposition: form-data; name="height"
Content-Type: application/octet-stream

80
-----------------------------mtynipxrmpegseog--
```