ci: add coverage step

Author: xenide

.github/workflows/ci.yml

@@ -68,3 +68,22 @@ jobs:
       - run: forge snapshot --check
         env:
           FOUNDRY_PROFILE: default
+
+  coverage:
+    needs: [test-unit]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - uses: foundry-rs/foundry-toolchain@v1
+        with:
+          version: nightly
+
+      - run: forge coverage --report lcov
+
+      - uses: codecov/codecov-action@v3
+        with:
+          fail_ci_if_error: true
+          files: ./lcov.info