[cleanup] Sort imports

Using https://github.com/PyCQA/isort

    isort -m VERTICAL_HANGING_INDENT --py 36 -l 80 --rr -n --tc .

yt_dlp/postprocessor/xattrpp.py

@@ -1,11 +1,11 @@
 from .common import PostProcessor
 from ..compat import compat_os_name
 from ..utils import (
-    hyphenate_date,
-    write_xattr,
     PostProcessingError,
     XAttrMetadataError,
     XAttrUnavailableError,
+    hyphenate_date,
+    write_xattr,
 )