[PATCH proxmox-backup] python3.12 compat: docs/_ext/proxmox-scanrefs.py: cast to string for re.sub()

[Jing Luo]

This fixes a FTBFS with python 3.12. We need to cast "filename" to string.

Sphinx version:   8.1.3
Python version:   3.12.8 (CPython)
Docutils version: 0.21.2
Jinja2 version:   3.1.3
Pygments version: 2.18.0

Last messages:
  copying assets...
  copying assets: done

  writing output... [  1%]
  GFDL

  writing output... [  2%]
  backup-client

Loaded extensions:
  sphinx.ext.mathjax (8.1.3)
  alabaster (0.7.16)
  sphinx.ext.graphviz (8.1.3)
  sphinx.ext.todo (8.1.3)
  proxmox-scanrefs (0.1)

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/sphinx/cmd/build.py", line 514, in build_main
    app.build(args.force_all, args.filenames)
  File "/usr/lib/python3/dist-packages/sphinx/application.py", line 380, in build
    self.builder.build_update()
  File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 355, in build_update
    self.build(['__all__'], to_build)
  File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 437, in build
    self.write(docnames, list(updated_docnames), method)
  File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 711, in write
    self.write_documents(docnames)
  File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 725, in write_documents
    self._write_serial(sorted_docnames)
  File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 744, in _write_serial
    self.write_doc(docname, doctree)
  File "/home/jing/proxmox-backup/build/docs/_ext/proxmox-scanrefs.py", line 92, in write_doc
    filename_html = re.sub('.rst', '.html', filename)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/__init__.py", line 186, in sub
    return _compile(pattern, flags).sub(repl, string, count)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: expected string or bytes-like object, got '_StrPath'

Signed-off-by: Jing Luo <jing at jing.rocks>
---
 docs/_ext/proxmox-scanrefs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/_ext/proxmox-scanrefs.py b/docs/_ext/proxmox-scanrefs.py
index 0d626561..680035e0 100644
--- a/docs/_ext/proxmox-scanrefs.py
+++ b/docs/_ext/proxmox-scanrefs.py
@@ -89,7 +89,7 @@ class ReflabelMapper(Builder):
 
                 if hasattr(node, 'expect_referenced_by_id') and len(node['ids']) > 1: # explicit labels
                     filename = self.env.doc2path(docname)
-                    filename_html = re.sub('.rst', '.html', filename)
+                    filename_html = re.sub('.rst', '.html', str(filename))
 
                     # node['ids'][0] contains a normalized version of the
                     # headline.  If the ref and headline are the same
-- 
2.47.1