Update isort requirement from ==5.* to ==6.*

Updates the requirements on [isort](https://github.com/pycqa/isort) to permit the latest version.
- [Release notes](https://github.com/pycqa/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/main/CHANGELOG.md)
- [Commits](PyCQA/isort@5.0.0...6.0.0)

---
updated-dependencies:
- dependency-name: isort
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements-dev.txt

@@ -4,7 +4,7 @@ build==1.2.2.post1
 # formatting and fixing
 autoflake==2.*
 black==24.*
-isort==5.*
+isort==6.*
 
 # tests
 coverage==7.*