Fix alignment of menu caret on Notebook user filter menu

The `Menu` container element was stretching to fill the entire grid
slot, which made the little menu "caret" show up too far to the right
when the menu was opened.

src/sidebar/components/NotebookView.js

@@ -135,7 +135,7 @@ function NotebookView({ loadAnnotationsService, streamer }) {
           {groupName}
         </h1>
       </header>
-      <div>
+      <div className="justify-self-start">
         <NotebookFilters />
       </div>
       <div className="flex items-center lg:justify-self-end text-lg font-medium">