fix: Dropdown misalign on scroll

Apparently this is a breaking change when Popper evolved into FloatingUI, you need to add autoUpdate manually now

REF: https://floating-ui.com/docs/migration#updating-the-position-automatically

Closes #15

app/soapbox/components/dropdown-menu/dropdown-menu.tsx

@@ -1,4 +1,4 @@
-import { offset, Placement, useFloating, flip, arrow, shift } from '@floating-ui/react';
+import { offset, Placement, useFloating, flip, arrow, shift, autoUpdate } from '@floating-ui/react';
 import clsx from 'clsx';
 import { supportsPassiveEvents } from 'detect-passive-events';
 import React, { useEffect, useMemo, useRef, useState } from 'react';
@@ -70,6 +70,7 @@ const DropdownMenu = (props: IDropdownMenu) => {
         element: arrowRef,
       }),
     ],
+    whileElementsMounted: !isOnMobile ? autoUpdate : undefined,
   });
 
   const handleClick: React.EventHandler<