chore: update coverage workflow to simplify and modernize setup (#15)

Revised the GitHub Actions workflow for code coverage by updating
dependencies, using modern, maintained actions, and improving
configuration clarity. Streamlined Rust installation and replaced manual
steps with dedicated actions for better reliability. Adjusted Codecov
settings for stricter error handling.

.github/workflows/coverage.yml

@@ -13,31 +13,24 @@ on:
     types:
       - created
 
+
 jobs:
-  test:
-    name: coverage
+  coverage:
     runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
     steps:
-      - uses: actions/checkout@v1
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          target: x86_64-unknown-linux-gnu
-          toolchain: nightly
-          components: llvm-tools-preview
-
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: |
+          rustup update nightly
       - name: Install cargo-llvm-cov
-        run: >
-          curl -LsSf 'https://github.com/taiki-e/cargo-llvm-cov/releases/download/v0.5.23/cargo-llvm-cov-x86_64-unknown-linux-musl.tar.gz'
-          | tar xzf -
-          && mv cargo-llvm-cov $HOME/.cargo/bin
-
-      - name: Run cargo-llvm-cov
-        run: cargo llvm-cov --doctests --all --all-features --lcov --output-path lcov.info
-
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo +nightly llvm-cov --all-features --workspace --codecov --doctests --output-path codecov.json
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3
         with:
-          directory: ./
-          fail_ci_if_error: false
-          files: ./lcov.info
-          verbose: true
+          token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos
+          files: codecov.json
+          fail_ci_if_error: true