chore: need to exclude migtest except for pg 15 on timescale plv8

Author: samrose

Diff for: migrations/tests/extensions/10-timescaledb.sql

@@ -1,7 +1,7 @@
 begin;
 do $_$
 begin
-  if not exists (select 1 from pg_extension where extname = 'orioledb') then
+  if current_setting('server_version_num')::integer >= 150000 and current_setting('server_version_num')::integer < 160000 then
     create extension if not exists timescaledb with schema "extensions";
   end if;
 end

Diff for: migrations/tests/extensions/13-plv8.sql

@@ -1,7 +1,7 @@
 begin;
 do $_$
 begin
-  if not exists (select 1 from pg_extension where extname = 'orioledb') then
+  if current_setting('server_version_num')::integer >= 150000 and current_setting('server_version_num')::integer < 160000 then
     create extension if not exists plv8 with schema "pg_catalog";
   end if;
 end