Remove incorrect name from release notes

This name was incorrect in the underlying commit message.  (The
correct name is already listed.)

Reported-by: Mark Wong

doc/src/sgml/release-15.sgml

@@ -3652,7 +3652,6 @@ Author: Etsuro Fujita <efujita@postgresql.org>
     <member>Floris Van Nee</member>
     <member>Frédéric Yhuel</member>
     <member>Gabriela Serventi</member>
-    <member>Gabriele Varrazzo</member>
     <member>Gaurab Dey</member>
     <member>Geoff Winkless</member>
     <member>Geoffrey Blake</member>