Enforce pre-commit to use a recent and fixed version of isort. (#5408)

Previously pre-commit was using any version of isort found on developer
machine. Now, used isort is from the official repository and version is
set to 5.7.0 (which is nowadays the latest release).

Co-authored-by: Akihiro Nitta <nitta@akihironitta.com>

Co-authored-by: Akihiro Nitta <nitta@akihironitta.com>

.pre-commit-config.yaml

@@ -22,14 +22,11 @@ repos:
       - id: trailing-whitespace
       - id: end-of-file-fixer
 
-  - repo: local
+  - repo: https://github.com/PyCQA/isort
+    rev: 5.7.0
     hooks:
       - id: isort
-        name: isort
-        entry: python -m isort
         args: [--settings-path, ./pyproject.toml]
-        language: system
-        types: [python]
 
   - repo: https://github.com/pre-commit/mirrors-mypy
     rev: v0.790