Update backends.yml

Author: DarthAffe

.github/workflows/backends.yml

@@ -245,7 +245,7 @@ jobs:
         if: ${{ matrix.build == 'cuda11' }}
         uses: Jimver/[email protected]
         with:
-          cuda: '11.8.0'
+          cuda: '11.7.1'
           method: network
           use-github-cache: false
           use-local-cache: false