Standardize formatting of ilastik project file parameter

model_server/ilastik.py

 import os
+from pathlib import Path
 
 import numpy as np
 import vigra
@@ -11,7 +12,8 @@ from model_server.model import ImageToImageModel, ParameterExpectedError
 class IlastikImageToImageModel(ImageToImageModel):
 
     def __init__(self, params, autoload=True):
-        self.project_file = str(params['project_file'])
+        self.project_file = Path(params['project_file'])
+        params['project_file'] = self.project_file.__str__()
         pap = conf.ilastik.paths['project_files'] / self.project_file
         self.project_file_abspath = pap
         if not pap.exists():