simplify CI

.github/workflows/coverage.yml

@@ -21,18 +21,8 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
-      - name: Install stable
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable-x86_64-unknown-linux-gnu
-          profile: minimal
-          override: true
-
-      - name: Generate Cargo.lock
-        uses: actions-rs/cargo@v1
-        with: { command: generate-lockfile }
-      - name: Cache Dependencies
-        uses: Swatinem/rust-cache@v1.2.0
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with: { toolchain: nightly }
 
       - name: Generate coverage file
         run: |