fix: use -F instead of -f for force=true in gh call

[bolinfest]

Apparently -F is the correct thing to use. From the code sample on

https://docs.github.com/en/rest/git/refs?apiVersion=2022-11-28#update-a-reference

gh api \
  --method PATCH \
  -H "Accept: application/vnd.github+json" \
  -H "X-GitHub-Api-Version: 2022-11-28" \
  /repos/OWNER/REPO/git/refs/REF \
   -f 'sha=aa218f56b14c9653891f9e74264a383fa43fefbd' -F "force=true"

Also, I ran the following locally and verified it worked:

export GITHUB_REPOSITORY=openai/codex
export GITHUB_SHA=305252b2fb2d57bb40a9e4bad269db9a761f7099
gh api \
  repos/${GITHUB_REPOSITORY}/git/refs/heads/latest-alpha-cli \
  -X PATCH \
  -f sha="${GITHUB_SHA}" \
  -F force=true

$GITHUB_REPOSITORY and $GITHUB_SHA should already be available as environment variables for the run step without having to be redeclared in the env section.