auto update: add git fetch command

src/components/AutoUpdateComponent.ts

@@ -31,6 +31,9 @@ export default class AutoUpdateComponent extends ApplicationComponent<void> {
         try {
             Logger.info('Starting auto update...');
 
+            // Fetch
+            await this.runCommand(`git fetch`);
+
             // Checkout new source
             await this.runCommand(`git checkout ${checkout_sha}`);