Bump squizlabs/php_codesniffer from 3.10.2 to 3.10.3 in /_backend (#3646

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Bumps [squizlabs/php_codesniffer](https://github.com/PHPCSStandards/PHP_CodeSniffer) from 3.10.2 to 3.10.3.
- [Release notes](https://github.com/PHPCSStandards/PHP_CodeSniffer/releases)
- [Changelog](https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/CHANGELOG.md)
- [Commits](PHPCSStandards/PHP_CodeSniffer@3.10.2...3.10.3)

---
updated-dependencies:
- dependency-name: squizlabs/php_codesniffer
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Lewis Goddard <[email protected]>