remove extra quotes

Author: rushabh-v

pandas/io/parsers.py

@@ -1910,7 +1910,7 @@ def __init__(self, src, **kwds):
                 self.names = list(range(self._reader.table_width))
         elif self.prefix:
             raise ValueError(
-                "Argument prefix must be None " "if argument header is not None"
+                "Argument prefix must be None if argument header is not None"
             )
 
         # gh-9755

pandas/tests/io/parser/test_header.py

@@ -26,7 +26,7 @@ def test_read_with_bad_header(all_parsers):
 
 def test_read_raises_on_header_prefix(all_parsers):
     parser = all_parsers
-    msg = "Argument prefix must be None " "if argument header is not None"
+    msg = "Argument prefix must be None if argument header is not None"
     with pytest.raises(ValueError, match=msg):
         s = StringIO("0,1\n2,3")
         parser.read_csv(s, header=0, prefix="_X")