Bump squizlabs/php_codesniffer to 3.9.0

Also, bump PHPCompatibility to current dev version (e5cd2e24)

We were using version 9.3.5 that is from December 2019. Since
then lots of new sniffs and compatibility with PHP 8.x versions
have been provided.

So, while not ideal, let's use the dev version in the mean time.

CHANGELOG.md

@@ -6,6 +6,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 The format of this change log follows the advice given at [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+### Changed
+- Update composer dependencies to current versions, notably `PHP_CodeSniffer` (3.9.0) and `PHPCompatibility` (e5cd2e24).
+
 ## [v3.3.15] - 2024-02-15
 ### Added
 - Function declaration lines are verified to have correct whitespace separation (1 space or 0 spaces) between all their parts.

composer.json

@@ -23,9 +23,9 @@
     ],
     "require": {
         "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
-        "squizlabs/php_codesniffer": "^3.8.1",
+        "squizlabs/php_codesniffer": "^3.9.0",
         "phpcsstandards/phpcsextra": "^1.2.1",
-        "phpcompatibility/php-compatibility": "dev-develop#306cd263"
+        "phpcompatibility/php-compatibility": "dev-develop#e5cd2e24"
     },
     "config": {
         "allow-plugins": {