Deprecate plugin's own ignore feature

in favor of Composer's own audit ignore feature

README.md

@@ -79,7 +79,7 @@ comes with minimal opt-out options.
 ### Silence warning about a deprecated- or unsupported package version in use
 
 > [!WARNING]
-> For Composer < 2.6.0 only. This feature will be removed when the minimum required Composer version gets bumped to >=2.6.0.
+> This feature is **deprecated** and it is going to be removed in version 2.0.0. Composer's built-in [audit ignore](https://getcomposer.org/doc/06-config.md#ignore) feature replaced it.
 
 In a project's root composer.json, under the `extra` property, add a definition like this:
 

src/Domain/PackageIgnore/PackageIgnoreRuleOptimizer.php

@@ -27,6 +27,9 @@ final protected function optimizePackageIgnoreRules(PackageIgnoreRuleProvider $p
         $rules = $provider->getIgnoreRules();
         /** @var \mxr576\ddqgComposerAudit\Domain\PackageIgnore\PackageIgnoreRule[] $rules */
         $rules = $rules instanceof \Traversable ? iterator_to_array($rules, false) : $rules;
+        if ([] !== $rules) {
+            trigger_error("Since 1.1.0 DDQG Composer Audit plugin's ignore features are deprecated, use Composer's built-in audit ignore feature instead. https://getcomposer.org/doc/06-config.md#ignore", E_USER_DEPRECATED);
+        }
         /** @var \ArrayObject<string,array<\mxr576\ddqgComposerAudit\Domain\PackageIgnore\PackageIgnoreRule>> $tmp */
         $tmp = array_reduce($rules,
             static function (\ArrayObject $carry, PackageIgnoreRule $item) {