Remove extra quote from 9.6RN

Author: dmpgpro

doc/src/sgml/release-pro-9.6.sgml

@@ -187,7 +187,7 @@
       based on the same <productname>PostgreSQL</productname> major release,
       a dump/restore is not required. If you are upgrading from
       <productname>Postgres Pro Standard</productname> 9.6.7.1 or
-      lower, you must also use the <filename>pgpro_upgrade"</filename> script provided
+      lower, you must also use the <filename>pgpro_upgrade</filename> script provided
       in this distribution. This script updates metadata information to handle
       catalog number format change introduced after 
       <productname>Postgres Pro Standard</productname> 9.6.4.1, as well as