troubleshoot sqlite tests (#67)

Author: shmax

test/SqliteAdapterTest.php

@@ -13,6 +13,7 @@ public function setUp(string $connection_name=null): void
     public function tearDown(): void
     {
         @unlink(self::InvalidDb);
+        parent::tearDown();
     }
 
     public static function tearDownAfterClass(): void

test/helpers/DatabaseTestCase.php

@@ -24,7 +24,7 @@ public function setUp(string $connection_name=null): void
         $this->original_default_connection = $config->get_default_connection();
         $connection_name ??= $this->original_default_connection;
 
-        //        $config->set_default_connection($connection_name);
+        $config->set_default_connection($connection_name);
 
         $this->original_date_class = $config->get_date_class();