fix broken task -- is this because of removed aliases/deprecations in mongodb 4?

schedules/tasks/prune.js

@@ -25,7 +25,7 @@ module.exports = {
 				'size': 0
 			}
 		}).toArray();
-		await Files.db.removeMany(query);
+		await Files.db.deleteMany(query);
 		await Promise.all(unreferenced.map(async file => {
 			debugLogs && console.log('Pruning', file._id);
 			return Promise.all(