Fix cleanup tests in PostgreSQL

lib/Database.php

@@ -1219,11 +1219,15 @@ class Database {
                 "SELECT
                     id, (select count(*) from arsse_subscriptions where feed = arsse_feeds.id) as subs
                 from arsse_feeds where id = ?".
+            "), latest_editions(article,edition) as (".
+                "SELECT article,max(id) from arsse_editions group by article".
             "), excepted_articles(id,edition) as (".
                 "SELECT
-                    arsse_articles.id, (select max(id) from arsse_editions where article = arsse_articles.id) as edition
+                    arsse_articles.id as id,
+                    latest_editions.edition as edition
                 from arsse_articles
                     join target_feed on arsse_articles.feed = target_feed.id
+                    join latest_editions on arsse_articles.id = latest_editions.article
                 order by edition desc limit ?".
             ") ".
             "DELETE from arsse_articles where

lib/Db/PostgreSQL/PDOStatement.php

@@ -12,7 +12,7 @@ class PDOStatement extends \JKingWeb\Arsse\Db\AbstractStatement {
     const BINDINGS = [
         "integer"   => "bigint",
         "float"     => "decimal",
-        "datetime"  => "timestamp",
+        "datetime"  => "timestamp(0) without time zone",
         "binary"    => "bytea",
         "string"    => "text",
         "boolean"   => "smallint", // FIXME: using boolean leads to incompatibilities with versions of SQLite bundled prior to PHP 7.3