[BUGFIX] Ensure PHP 8.4 compatibility for nullable parameters

Ensure that parameters that have a `null` default value also
have `null` as part of their type annotations.

Also remove native type declarations for nullable parameters
(as nullable parameters are not possible with some of the PHP
versions we currently support).

https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated

Fixes #634

Author: oliverklee

src/CSSList/CSSList.php

@@ -286,8 +286,8 @@ public function append($oItem)
      * Splices the list of contents.
      *
      * @param int $iOffset
-     * @param int $iLength
-     * @param array<int, RuleSet|CSSList|Import|Charset> $mReplacement
+     * @param int|null $iLength
+     * @param array<int, RuleSet|CSSList|Import|Charset>|null $mReplacement
      *
      * @return void
      */

src/CSSList/Document.php

@@ -78,7 +78,7 @@ public function getAllRuleSets()
     /**
      * Returns all `Value` objects found recursively in `Rule`s in the tree.
      *
-     * @param CSSList|RuleSet|string $mElement
+     * @param CSSList|RuleSet|string|null $mElement
      *        the `CSSList` or `RuleSet` to start the search from (defaults to the whole document).
      *        If a string is given, it is used as rule name filter.
      * @param bool $bSearchInFunctionArguments whether to also return Value objects used as Function arguments.
@@ -155,7 +155,7 @@ public function createShorthands()
      *
      * @return string
      */
-    public function render(OutputFormat $oOutputFormat = null)
+    public function render($oOutputFormat = null)
     {
         if ($oOutputFormat === null) {
             $oOutputFormat = new OutputFormat();

src/Parser.php

@@ -21,7 +21,7 @@ class Parser
      * @param Settings|null $oParserSettings
      * @param int $iLineNo the line number (starting from 1, not from 0)
      */
-    public function __construct($sText, Settings $oParserSettings = null, $iLineNo = 1)
+    public function __construct($sText, $oParserSettings = null, $iLineNo = 1)
     {
         if ($oParserSettings === null) {
             $oParserSettings = Settings::create();

src/Renderable.php

@@ -12,7 +12,7 @@ public function __toString();
     /**
      * @return string
      */
-    public function render(OutputFormat $oOutputFormat);
+    public function render($oOutputFormat);
 
     /**
      * @return int

src/RuleSet/RuleSet.php

@@ -102,7 +102,7 @@ public function getLineNo()
      *
      * @return void
      */
-    public function addRule(Rule $oRule, Rule $oSibling = null)
+    public function addRule(Rule $oRule, $oSibling = null)
     {
         $sRule = $oRule->getRule();
         if (!isset($this->aRules[$sRule])) {