Switch clippy to beta

Once 1.62 is relased, we can switch back to stable.

Author: fanninpm

.github/workflows/ci.yaml

@@ -220,7 +220,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
             profile: minimal
-            toolchain: nightly
+            toolchain: beta
             components: rustfmt, clippy
             override: true
       - name: run rustfmt