✅ Add XML coverage report for GitHub Actions (#1737)

scripts/test.sh

@@ -7,4 +7,4 @@ bash ./scripts/lint.sh
 # Check README.md is up to date
 diff --brief docs/en/docs/index.md README.md
 export PYTHONPATH=./docs_src
-pytest --cov=fastapi --cov=tests --cov=docs/src --cov-report=term-missing tests ${@}
+pytest --cov=fastapi --cov=tests --cov=docs/src --cov-report=term-missing --cov-report=xml tests ${@}