pip (deps-dev): bump black from 26.3.0 to 26.3.1

Bumps [black](https://github.com/psf/black) from 26.3.0 to 26.3.1.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@26.3.0...26.3.1)

---
updated-dependencies:
- dependency-name: black
  dependency-version: 26.3.1
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

poetry.lock

@@ -16,14 +16,14 @@ python = "^3.13"
 
 [tool.poetry.group.ci.dependencies]
 flake8 = "^7.3.0"
-black = "^26.3.0"
+black = "^26.3.1"
 
 [tool.poetry.group.test.dependencies]
 pytest-nhsd-apim = "^6.0.7"
 
 [tool.poetry.group.dev.dependencies]
 flake8 = "^7.3.0"
-black = "^26.3.0"
+black = "^26.3.1"
 jinja2 = "^3.1.6"
 PyYAML = "^6.0.1"
 docopt = "^0.6.2"