Add concurrency to ci.yml

And use sparse registry

Signed-off-by: Jiahao XU <[email protected]>

.github/workflows/ci.yml

@@ -2,6 +2,7 @@ name: ci
 
 env:
   CARGO_TERM_COLOR: always
+  CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
 
 on:
   merge_group:
@@ -12,6 +13,10 @@ on:
       - '.gitignore'
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref || github.event.pull_request.number || github.sha }}-${{ inputs.additional_key }}
+  cancel-in-progress: true
+
 jobs:
   fmt:
     runs-on: ubuntu-latest