This reverts commit 378f67d678, reversing
changes made to 5e3bc9f2b9.
Direct arithmetic operations (like +, -, *, /) are not directly
supported within GitHub Actions expressions inside ${{ ... }}
syntax.
Invalid workflow file: .github/workflows/main.yml#L1
(Line: 153, Col: 12): Unexpected symbol: '+'. Located at position 11
within expression: matrix.nr + 1, (Line: 301, Col: 12): Unexpected
symbol: '+'. Located at position 11 within expression: matrix.nr + 1