[cleanup] Sort imports

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

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

yt_dlp/postprocessor/sponsorblock.py

@@ -1,6 +1,6 @@
-from hashlib import sha256
 import json
 import re
+from hashlib import sha256
 
 from .ffmpeg import FFmpegPostProcessor
 from ..compat import compat_urllib_parse_urlencode