Update test_fstring.py

Author: MeGaGiGaGon

Lib/test/test_fstring.py

@@ -1370,7 +1370,7 @@ def test_conversions(self):
         for conv in ' s', ' s ':
             self.assertAllRaise(SyntaxError,
                                 "f-string: conversion type must come right after the"
-                                " exclamanation mark",
+                                " exclamation mark",
                                 ["f'{3!" + conv + "}'"])
 
         self.assertAllRaise(SyntaxError,