Bump black from 20.8b1 to 26.3.1

Bumps [black](https://github.com/psf/black) from 20.8b1 to 26.3.1.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](https://github.com/psf/black/commits/26.3.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ beautifulsoup4==4.8.1
 soupsieve==1.9.5
 esprima==4.0.1
 click==7.1.2
-black==20.8b1
+black==26.3.1
 flake8==3.8.3
 pytest==5.4.3
 cumulusci