tests: Use correct encoding for path

Before this change, build_temp_workspace() would always encode a path
using UTF-8 and the strict error handler [1]. Most of the time, this is
fine, but systems do not necessarily use UTF-8 and the strict error
handler for paths [2].

[1]: <https://docs.python.org/3.12/library/stdtypes.html#str.encode>
[2]: <https://docs.python.org/3.12/glossary.html#term-filesystem-encoding-and-error-handler>

tests/common.py

@@ -58,7 +58,7 @@ def build_temp_workspace(files):
     tempdir = tempfile.mkdtemp(prefix='yamllint-tests-')
 
     for path, content in files.items():
-        path = os.path.join(tempdir, path).encode('utf-8')
+        path = os.fsencode(os.path.join(tempdir, path))
         if not os.path.exists(os.path.dirname(path)):
             os.makedirs(os.path.dirname(path))