Bump slevomat/coding-standard in the dependencies group (#508)

Bumps the dependencies group with 1 update: [slevomat/coding-standard](https://github.com/slevomat/coding-standard).


Updates `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
  dependency-group: dependencies
...

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

Author: dependabot[bot]