fixed postgres tests

source/orm/orm/session.cpp

@@ -30,13 +30,20 @@ utils::result<void, utils::error> session::create_schema() const {
   return utils::ok<void>();
 }
 
-void session::drop_table(const std::string &table_name) const {
+utils::result<void, utils::error> session::drop_table(const std::string &table_name) const {
   auto c = pool_.acquire();
   if (!c.valid()) {
     throw std::logic_error("no database connection available");
   }
 
-  // c->query(*schema_).drop().table(table_name).execute();
+  auto result = query::query::drop()
+    .table(table_name)
+    .execute(*c);
+  if (result.is_error()) {
+    return utils::failure(result.err());
+  }
+
+  return utils::ok<void>();
 }
 
 utils::result<sql::query_result<sql::record>, utils::error> session::fetch(const sql::query_context &q) const