Fix typo in GCSSDK superbuild

[Shelnutt2]

Fix typo in GCSSDK superbuild

[github-actions]

The backport to release-2.0.4 failed:

The process 'git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release-2.0.4 release-2.0.4
# Navigate to the new working tree
cd .worktrees/backport-release-2.0.4
# Create a new branch
git switch --create backport-1665-to-release-2.0.4
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick e327e8615760cc093e0d0742621613442a26e811
# Push it to GitHub
git push --set-upstream origin backport-1665-to-release-2.0.4
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-2.0.4

Then, create a pull request where the base branch is release-2.0.4 and the compare/head branch is backport-1665-to-release-2.0.4.