use stale swr and disable revalidation

components/previews/MarkdownPreview.tsx

@@ -1,6 +1,4 @@
 import { useEffect, FunctionComponent } from 'react'
-import axios from 'axios'
-import useSWR from 'swr'
 import Prism from 'prismjs'
 import ReactMarkdown from 'react-markdown'
 import gfm from 'remark-gfm'
@@ -13,11 +11,10 @@ import 'katex/dist/katex.min.css'
 import FourOhFour from '../FourOhFour'
 import Loading from '../Loading'
 import DownloadBtn from '../DownloadBtn'
-
-const fetcher = (url: string) => axios.get(url).then(res => res.data)
+import { useStaleSWR } from '../../utils/tools'
 
 const MarkdownPreview: FunctionComponent<{ file: any; standalone?: boolean }> = ({ file, standalone = true }) => {
-  const { data, error } = useSWR(file['@microsoft.graph.downloadUrl'], fetcher)
+  const { data, error } = useStaleSWR(file['@microsoft.graph.downloadUrl'])
 
   useEffect(() => {
     if (typeof window !== 'undefined') {