Don't try to upload coverage if CI is run via workflow dispatch on a fork (python-attrs#385)

Author: AlexWaygood

.github/workflows/main.yml

@@ -42,6 +42,7 @@ jobs:
 
       - name: "Upload coverage to Codecov"
         # if: "contains(env.USING_COVERAGE, matrix.python-version)"
+        if: github.repository == 'python-attrs/cattrs'
         uses: "codecov/codecov-action@v1"
         with:
           fail_ci_if_error: true