Move webhook to project notification type

app/Schema/Postgres.php

@@ -6,7 +6,20 @@ use PDO;
 use Kanboard\Core\Security;
 use Kanboard\Model\Link;
 
-const VERSION = 71;
+const VERSION = 72;
+
+function version_72($pdo)
+{
+    $pdo->exec("
+        CREATE TABLE project_has_notification_types (
+            id SERIAL PRIMARY KEY,
+            project_id INTEGER NOT NULL,
+            notification_type VARCHAR(50),
+            FOREIGN KEY(project_id) REFERENCES projects(id) ON DELETE CASCADE,
+            UNIQUE(project_id, notification_type)
+        )
+    ");
+}
 
 function version_71($pdo)
 {