Fix: make format to expand tabs

There is similar issue as what was fixed in autopep8 with the initial
LFS migration: `git ls-tree` running to gather all files contains files
with non-ascii names, such as some non-latin utf-8 files in the tests.

Decode the ls-tree using utf-8 for C code format as well.

Pull Request: https://projects.blender.org/blender/blender/pulls/138488

tools/utils_maintenance/clang_format_paths.py

@@ -96,7 +96,7 @@ def source_files_from_git(paths: Sequence[str], changed_only: bool) -> list[str]
     else:
         cmd = ("git", "ls-tree", "-r", "HEAD", *paths, "--name-only", "-z")
     files = subprocess.check_output(cmd).split(b'\0')
-    return [f.decode('ascii') for f in files]
+    return [f.decode('utf-8') for f in files]
 
 
 def convert_tabs_to_spaces(files: Sequence[str]) -> None: