sparse registry has been stable for a bit now

RalfJung · RalfJung · commit 451c33c2c984 · 2023-07-26T09:10:50.000+02:00
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -12,9 +12,6 @@ on:
   schedule:
     - cron: '11 5 * * *' # At 5:11 UTC every day.
 
-env:
-  CARGO_UNSTABLE_SPARSE_REGISTRY: 'true'
-
 defaults:
   run:
     shell: bash
