chore: untrack .speakeasy/workflow.local.yaml

The file was meant to be gitignored (see #37 which added the gitignore
entry + workflow.local.example template + bin/setup-local helper), but
the original tracked copy was never removed. CI picks up its local-path
source URLs (e.g., `../Gusto-Partner-API/...`) and fails on the local
target. Drop the tracked copy; the gitignore entry already prevents
re-adds.

Author: azrosen92