ci: fix shard numbering using 1-based matrix values

GitHub Actions expressions don't support arithmetic operators so
'matrix.shard + 1' was invalid. Switch the matrix to [1, 2, 3, 4]
so the job name, step name, and log output all read '1 of 4' through
'4 of 4'. The PowerShell script subtracts 1 locally for the 0-based
slice math.

Co-authored-by: Copilot <[email protected]>

0 files changed, 0 insertions, 0 deletions