Trial fix for old cross-version upgrades.

Per buildfarm and reports, it seems that 9.X to 18 upgrades were
failing after commit 1fd1bd8710 due to an incorrect regex. Loosen the
regex to accommodate older versions.

Reported-by: vignesh C <vignesh21@gmail.com>
Reported-by: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://postgr.es/m/CALDaNm3GUs+U8Nt4S=V5zmb+K8-RfAc03vRENS0teeoq0Lc6Tw@mail.gmail.com
Discussion: https://postgr.es/m/ea4cbbc1-c5a5-43d1-9618-8ff3f2155bfe@dunslane.net

src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm

@@ -296,7 +296,7 @@ sub adjust_old_dumpfile
 
 	# Same with version argument to pg_restore_relation_stats() or
 	# pg_restore_attribute_stats().
-	$dump =~ s ['version', '${old_version}\d{4}'::integer,]
+	$dump =~ s ['version', '\d+'::integer,]
 		['version', '000000'::integer,]mg;
 
 	if ($old_version < 16)
@@ -633,7 +633,7 @@ sub adjust_new_dumpfile
 
 	# Same with version argument to pg_restore_relation_stats() or
 	# pg_restore_attribute_stats().
-	$dump =~ s ['version', '\d{6}'::integer,]
+	$dump =~ s ['version', '\d+'::integer,]
 		['version', '000000'::integer,]mg;
 
 	if ($old_version < 14)