Retry rust audit as well

https://github.com/rust-analyzer/rust-analyzer/runs/511553989?check_suite_focus=true#step:3:6

.github/workflows/ci.yaml

@@ -11,6 +11,10 @@ jobs:
   rust-audit:
     name: Audit Rust vulnerabilities
     runs-on: ubuntu-latest
+    env:
+      RUSTUP_MAX_RETRIES: 10
+      CARGO_NET_RETRY: 10
+
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2