CI: Implement branch coverage using llcov

.github/workflows/codecov.yml

@@ -1,42 +1,23 @@
-on:
-  push:
-    branches:
-      - main
-
 name: Code coverage check
 
-jobs:
+on: [pull_request, push]
 
+jobs:
   coverage:
-    name: Code Coverage
-    # https://github.com/actions/virtual-environments
-    runs-on: ubuntu-20.04
-    strategy:
-      matrix:
-        rust-version: [1.78.0]
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
     steps:
-      - name: Checkout sources
-        uses: actions/checkout@v3
-      - name: Install stable toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: ${{ matrix.rust-version }}
-          target: wasm32-unknown-unknown
-          override: true
-      - name: Install tarpaulin
-        uses: actions-rs/cargo@v1
-        with:
-          command: install
-          args: cargo-tarpaulin --version 0.30.0
-      - run: make build
-      - name: Run code coverage check with tarpaulin
-        uses: actions-rs/cargo@v1
-        with:
-          command: tarpaulin
-          args: --all-features --workspace --timeout 120 --out Xml --exclude soroban-token-contract
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: rustup update stable
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo llvm-cov --all-features --workspace --codecov --output-path codecov.json
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v3
         with:
-          token: ${{ secrets.CODECOV_TOKEN }}
-          file: ./cobertura.xml
+          token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos
+          files: lcov.info
+          fail_ci_if_error: true