use stable

Author: Jakobzs

.github/workflows/coverage.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: nightly
+          toolchain: stable
           components: llvm-tools-preview
       - name: Install llvm-cov
         uses: taiki-e/install-action@v2