increase the version string buffer in mariadb-upgrade

there's no point in keeping it small.

this fixes numerous test failures in preview branches with
versions like 10.7.0-MDEV-xxxx-short-feature-description-MariaDB

client/mysql_upgrade.c

@@ -70,7 +70,7 @@ static char **defaults_argv;
 
 static my_bool not_used; /* Can't use GET_BOOL without a value pointer */
 
-char upgrade_from_version[sizeof("10.20.456-MariaDB")+1];
+char upgrade_from_version[1024];
 
 static my_bool opt_write_binlog;