The workflow is not valid. .github/workflows/rust.yml (Line: 62, Col: 14): The expression is not closed. An unescaped ${{ sequence was found, but the closing }} sequence was not found. .github/workflows/rust.yml (Line: 64, Col: 14): Unexpected symbol: ''unstable''. Located at position 42 within expression: matrix.rust == 'nightly' && '--features' 'unstable'