Remove ENV_PATH on Black action completion.

CHANGES.md

@@ -50,6 +50,8 @@
   [official pre-commit mirror](https://github.com/psf/black-pre-commit-mirror). Swapping
   `https://github.com/psf/black` to `https://github.com/psf/black-pre-commit-mirror` in
   your `.pre-commit-config.yaml` will make Black about 2x faster (#3828)
+- The `.black.env` folder specified by `ENV_PATH` will now be removed on the completion
+  of the GitHub Action. (#3759)
 
 ### Documentation
 

action/main.py

@@ -1,5 +1,6 @@
 import os
 import shlex
+import shutil
 import sys
 from pathlib import Path
 from subprocess import PIPE, STDOUT, run
@@ -73,5 +74,6 @@
         stderr=STDOUT,
         encoding="utf-8",
     )
+shutil.rmtree(ENV_PATH, ignore_errors=True)
 print(proc.stdout)
 sys.exit(proc.returncode)