Use read_info_from_image in postprocessing

Avoids bad keys such as `exif` ending up in the "PNG info" passed forward

modules/postprocessing.py

@@ -54,7 +54,9 @@ def run_postprocessing(extras_mode, image, image_folder, input_dir, output_dir,
     for image, name in zip(image_data, image_names):
         shared.state.textinfo = name
 
-        existing_pnginfo = image.info or {}
+        parameters, existing_pnginfo = images.read_info_from_image(image)
+        if parameters:
+            existing_pnginfo["parameters"] = parameters
 
         pp = scripts_postprocessing.PostprocessedImage(image.convert("RGB"))