Fix typo in 3.10.0a7.rst (GH-25340)

Author: skirpichev

Misc/NEWS.d/3.10.0a7.rst

@@ -534,7 +534,7 @@ during connection setup.
 .. nonce: cee_X5
 .. section: Library
 
-Improve performance of class:`fractions.Fraction` arithmetics for large
+Improve performance of :class:`fractions.Fraction` arithmetics for large
 components.  Contributed by Sergey B. Kirpichev.
 
 ..