Bump slevomat/coding-standard from 8.19.1 to 8.20.0

Bumps [slevomat/coding-standard](https://github.com/slevomat/coding-standard) from 8.19.1 to 8.20.0.
- [Release notes](https://github.com/slevomat/coding-standard/releases)
- [Commits](slevomat/coding-standard@8.19.1...8.20.0)

---
updated-dependencies:
- dependency-name: slevomat/coding-standard
  dependency-version: 8.20.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]