Minor bug fix in the post-release script (#2705)

Summary:
Pull Request resolved: #2705

imported-using-ghimport

Test Plan: Imported from OSS

Reviewed By: mergennachin

Differential Revision: D55408595

Pulled By: guangy10

fbshipit-source-id: 36a202c31cc4ca660bcbacad63f00fc32132e3b4

Author: guangy10

scripts/release/apply-release-changes.sh

@@ -26,7 +26,7 @@ RELEASE_BRANCH="release/${RELEASE_VERSION}"
 
 if git ls-remote --exit-code origin ${RELEASE_BRANCH} >/dev/null 2>&1; then
   echo "Check out to Release Branch '${RELEASE_BRANCH}'"
-  git checkout -b ${RELEASE_BRANCH}
+  git checkout ${RELEASE_BRANCH}
 else
   echo "Error: Remote branch '${RELEASE_BRANCH}' not found. Please run 'cut-release-branch.sh' first."
   exit 1