The workflow is not valid. .github/workflows/workflow.yml (Line: 50, Col: 16): Unrecognized named-value: 'matrix'. Located at position 1 within expression: matrix.stuff.flake .github/workflows/workflow.yml (Line: 54, Col: 16): Unrecognized named-value: 'matrix'. Located at position 1 within expression: matrix.stuff.flake