coverage: add coverage CI action

.github/workflows/kcov.yml

@@ -0,0 +1,46 @@
+name: Code Coverage
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+          submodules: true
+
+      - uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: master
+
+      - run: zig version
+      - run: zig env
+
+      - name: Build
+        run: zig build
+
+      - name: Install kcov
+        run: |
+          sudo apt-get update
+          sudo apt-get install kcov
+
+      - name: Run Tests with kcov
+        run: |
+          mkdir -p zig-out/kcov
+          zig build test -Dgenerate_coverage
+          tree zig-out
+          
+      - uses: codecov/codecov-action@v3
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          directory: zig-out/kcov/kcov-merged
+          fail_ci_if_error: true
+          verbose: true
+