Removes strict type declaration to publish the plugin

ScheduleReportSlack.php

@@ -7,8 +7,6 @@
  * @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace Piwik\Plugins\Slack;
 
 class ScheduleReportSlack

Slack.php

@@ -7,8 +7,6 @@
  * @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace Piwik\Plugins\Slack;
 
 use Piwik\Log\LoggerInterface;

SlackApi.php

@@ -7,8 +7,6 @@
  * @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace Piwik\Plugins\Slack;
 
 use Piwik\Container\StaticContainer;