Update export.py

Transformed the f variable into a string on the export onnx. This bug was making it impossible to export any models in .onnx, since it was making the typehint not accept the users input as it is specified in the functions documentation

Signed-off-by: Luis Filipe Araujo de Souza <58831491+Doquey@users.noreply.github.com>

export.py

@@ -155,7 +155,7 @@ def export_onnx(model, im, file, opset, dynamic, simplify, prefix=colorstr('ONNX
     import onnx
 
     LOGGER.info(f'\n{prefix} starting export with onnx {onnx.__version__}...')
-    f = file.with_suffix('.onnx')
+    f = str(file.with_suffix('.onnx'))
 
     output_names = ['output0', 'output1'] if isinstance(model, SegmentationModel) else ['output0']
     if dynamic: