Update isort to avoid poetry-core breaking change

poetry-core 1.5.0 introduced a breaking change (in a minor version) by
altering parsing of `extras` metadata (python-poetry/poetry-core#542).
This broke package builds from source for isort (PyCQA/isort#2077),
which is how pre-commit installs isort.

This commit will update pre-commit to the fixed version of isort.

.pre-commit-config.yaml

@@ -11,7 +11,7 @@ repos:
       - id: flake8
         args: [--max-line-length=88]
   - repo: https://github.com/pycqa/isort
-    rev: 5.11.4
+    rev: 5.12.0
     hooks:
       - id: isort
         args: [--filter-files]