Fix disabling spellcheck with <Input>

ts/components/Input.tsx

@@ -1,4 +1,4 @@
-// Copyright 2021 Signal Messenger, LLC
+// Copyright 2021-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import type { ClipboardEvent, ReactNode } from 'react';
@@ -203,7 +203,7 @@ export const Input = forwardRef<
         isLarge && getClassName('__input--large')
       ),
       disabled: Boolean(disabled),
-      spellcheck: disableSpellcheck ? 'false' : 'true',
+      spellCheck: !disableSpellcheck,
       onChange: handleChange,
       onKeyDown: handleKeyDown,
       onPaste: handlePaste,