add codecov coverage

Author: brunompacheco

.github/workflows/tests.yml

@@ -31,3 +31,13 @@ jobs:
       - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
+        with:
+          annotate: true
+          coverage: true
+      - uses: julia-actions/julia-processcoverage@v1
+        with:
+          directories: src
+      - uses: codecov/codecov-action@v2
+        with:
+          files: lcov.info
+          token: ${{ secrets.CODECOV_TOKEN }}