[GitHub Actions] Add missing fetch (#26)

diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index c2e0fd8..7be3317 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -60,7 +60,8 @@
           git config user.email "$(git log -1 --pretty=format:%ae)"
           git remote add deploy \
             https://x-access-token:${GITHUB_TOKEN}@github.com/${ORIGIN}.git
-          if ! git checkout ${TARGET_BRANCH}; then
+          git fetch deploy
+          if ! git checkout --track deploy/${TARGET_BRANCH}; then
             git checkout -b ${TARGET_BRANCH} remotes/origin/asf-site
           fi
           rsync \