Upgrade to Nginx 1.26.3

[giohappy]

Aligns with GeoNode/geonode#13323

[github-actions]

The backport to 4.4.x failed:

The process '/usr/bin/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-4.4.x 4.4.x
# Navigate to the new working tree
cd .worktrees/backport-4.4.x
# Create a new branch
git switch --create backport-580-to-4.4.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 bca5d54a38c42363db33035cc95a3446ca9a7452
# Push it to GitHub
git push --set-upstream origin backport-580-to-4.4.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-4.4.x

Then, create a pull request where the base branch is 4.4.x and the compare/head branch is backport-580-to-4.4.x.