Fix nullable type parameter deprecation warnings on PHP 8.4 (#128)

* fix: nullable type parameter deprecation on PHP 8.4

Author: jamesdb

src/Contracts/SettingsManagerContract.php

@@ -23,7 +23,7 @@ public function apply(array $settings = []): self;
      * @param mixed $default default value to return if the path does not exist
      * @return mixed
      */
-    public function get(string $path = null, $default = null);
+    public function get(?string $path = null, $default = null);
 
     /**
      * Obtains multiple items by their paths.
@@ -55,7 +55,7 @@ public function update(string $path, $value): self;
      * @param string|null $path
      * @return \Glorand\Model\Settings\Contracts\SettingsManagerContract
      */
-    public function delete(string $path = null): self;
+    public function delete(?string $path = null): self;
 
     /**
      * Deletes multiple setting items in a single operation.

src/Managers/AbstractSettingsManager.php

@@ -122,7 +122,7 @@ public function has(string $path): bool
      * @param null $default
      * @return array|\ArrayAccess|mixed
      */
-    public function get(string $path = null, $default = null)
+    public function get(?string $path = null, $default = null)
     {
         return $path ? Arr::get($this->all(), $path, $default) : $this->all();
     }
@@ -132,7 +132,7 @@ public function get(string $path = null, $default = null)
      * @param null $default
      * @return array
      */
-    public function getMultiple(iterable $paths = null, $default = null): array
+    public function getMultiple(?iterable $paths = null, $default = null): array
     {
         $array = [];
         $allFlattened = $this->allFlattened();
@@ -178,7 +178,7 @@ public function update(string $path, $value): SettingsManagerContract
      * @param string|null $path
      * @return \Glorand\Model\Settings\Contracts\SettingsManagerContract
      */
-    public function delete(string $path = null): SettingsManagerContract
+    public function delete(?string $path = null): SettingsManagerContract
     {
         if (!$path) {
             $settings = [];

src/Traits/HasSettingsRedis.php

@@ -32,7 +32,7 @@ public function getSettingsValue(): array
         return is_array($value) ? $value : [];
     }
 
-    public function cacheKey(string $key = null): string
+    public function cacheKey(?string $key = null): string
     {
         return sprintf(
             "r-k-%s:%s",