Submit coverage data to codecov

Author: djc

.github/workflows/main.yml

@@ -73,3 +73,10 @@ jobs:
           toolchain: stable
           override: true
       - uses: actions-rs/tarpaulin@v0.1
+      - uses: codecov/codecov-action@v1.0.2
+        with:
+          token: ${{secrets.CODECOV_TOKEN}}
+      - uses: actions/upload-artifact@v1
+        with:
+          name: code-coverage-report
+          path: cobertura.xml