setup-python/.github/python.json

{
    "problemMatcher": [
        {
            "owner": "python",
            "pattern": [
                {
                    "regexp": "^  File \"([^\"]*)\", line (\\d+).*",
                    "file": 1,
                    "line": 2
                },
                {
                    "regexp": "^    .*$"
                },
                {
                    "regexp": "^(?!  File)(.*)\\s*$",
                    "message": 1
                }
            ]
        }
    ]
}