added tarpaulin for code coverage

Author: siddharthqs

.github/workflows/rust.yml

@@ -20,6 +20,17 @@ jobs:
       run: cargo build --verbose
     - name: Run tests
       run: cargo test --verbose
+    - name: Install Tarpaulin.
+      run: cargo install cargo-tarpaulin
+    - name: Generate code coverage report.
+      run:
+          cargo tarpaulin
+          --verbose
+          --all-features
+          --workspace
+          --timeout 120
+          --out Xml
+          --exclude-files 'src/main.rs'
     - name: Upload coverage reports to Codecov
       uses: codecov/codecov-action@v3
       env: