fix(pytools): run diff-index in the asf-site-next worktree

The diff-index call was missing cwd=site, so it checked the main repo
(always clean after checkout) instead of the asf-site-next worktree,
causing commit+push to be skipped. The bug was masked until now by
scripts/replace.js mutating the main tree in place; removing replace.js
exposed it and stopped the site from updating.

BUILD_ALL_VERSION=1

Author: lhotari

tools/pytools/lib/execute/site_uploader.py

@@ -48,7 +48,7 @@ def _do_push(msg: str, site: Path, branch: str):
     git = find_command('git', msg="git is required")
 
     run(git, 'add', '-A', '.', cwd=site)
-    changed = run(git, 'diff-index', '--quiet', 'HEAD', codes={0, 1}).returncode
+    changed = run(git, 'diff-index', '--quiet', 'HEAD', codes={0, 1}, cwd=site).returncode
     print(f'changed: {changed}')
 
     run(git, 'status', cwd=site)