Update slevomat/coding-standard requirement from ^7.0 to ^8.4

[dependabot[bot]]

Updates the requirements on slevomat/coding-standard to permit the latest version.

Release notes

Sourced from slevomat/coding-standard's releases.

8.4.0

🔧 Improvements

• Support of phpstan/phpdoc-parser 1.7.0

🐛 Fixes

• Fixed detection of some PHP 8.1 types
• SlevomatCodingStandard.PHP.RequireNowdoc: Accepts escaped sequences (thanks to @​dg)
• SlevomatCodingStandard.Functions.RequireSingleLineCall: Skip calls with multi-line double-quoted string (thanks to @​schlndh)
• SlevomatCodingStandard.PHP.UselessParentheses: Fixed false positive with xor
• SlevomatCodingStandard.Operators.RequireCombinedAssignmentOperator: Try to ignore string offsets

Commits

• 02f2732 phpstan/phpdoc-parser 1.7
• a2ea28b SlevomatCodingStandard.Operators.RequireCombinedAssignmentOperator: Try to ig...
• ea4153e Updated dependencies
• e332564 Fixed detection of some PHP 8.1 types
• eb48bcb SlevomatCodingStandard.PHP.UselessParentheses: Ignore xor
• cfe3d03 SlevomatCodingStandard.Functions.RequireSingleLineCallSniff: skip calls with ...
• 94a9364 RequireNowdocSniff: accepts escaped sequences
• 8c671af Update composer.json
• 56a4b20 Reflect current major version in README
• a14df43 Updated dependencies
• Additional commits viewable in compare view

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