Fix tests

Author: ppinchuk

tests/web/test_web_file_loader.py

@@ -29,6 +29,7 @@ def __init__(self, read_return):
         self.read_return = read_return
         self.content_type = "application/pdf"
         self.charset = "utf-8"
+        self.headers = {}
 
     async def read(self):
         """Return what class was initialized with."""