Bump black from 26.3.0 to 26.3.1 in /envs (#125)

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:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

envs/requirements.txt

@@ -15,7 +15,7 @@ attrs==25.4.0
 babel==2.18.0
 backports.tarfile==1.2.0
 backports.zstd==1.3.0
-black==26.3.0
+black==26.3.1
 branca==0.8.2
 Brotli==1.2.0
 certifi==2026.2.25