Allow only callable or null for macro value

src/Carbon/CarbonInterval.php

@@ -1479,7 +1479,7 @@ public function isEmpty(): bool
      * echo CarbonInterval::hours(2)->twice();
      * ```
      */
-    public static function macro(string $name, object|callable|null $macro): void
+    public static function macro(string $name, ?callable $macro): void
     {
         static::$macros[$name] = $macro;
     }

src/Carbon/CarbonPeriod.php

@@ -524,7 +524,7 @@ private static function makeInterval(mixed $input): ?CarbonInterval
      * echo CarbonPeriod::since('2011-05-12')->until('2011-06-03')->middle();
      * ```
      */
-    public static function macro(string $name, object|callable|null $macro): void
+    public static function macro(string $name, ?callable $macro): void
     {
         static::$macros[$name] = $macro;
     }

src/Carbon/Factory.php

@@ -319,7 +319,7 @@ public function getHumanDiffOptions(): int
      * echo $factory->yesterday()->hours(11)->userFormat();
      * ```
      */
-    public function macro(string $name, object|callable|null $macro): void
+    public function macro(string $name, ?callable $macro): void
     {
         $macros = $this->getSettings()['macros'] ?? [];
         $macros[$name] = $macro;
@@ -375,7 +375,7 @@ public function hasMacro(string $name): bool
     /**
      * Get the raw callable macro registered globally for a given name.
      */
-    public function getMacro(string $name): object|callable|null
+    public function getMacro(string $name): ?callable
     {
         return $this->getSettings()['macros'][$name] ?? null;
     }

src/Carbon/Traits/Macro.php

@@ -27,6 +27,8 @@ trait Macro
     /**
      * Register a custom macro.
      *
+     * Pass null macro to remove it.
+     *
      * @example
      * ```
      * $userSettings = [
@@ -38,10 +40,8 @@ trait Macro
      * });
      * echo Carbon::yesterday()->hours(11)->userFormat();
      * ```
-     *
-     * Pass null macro to remove it.
      */
-    public static function macro(string $name, object|callable|null $macro): void
+    public static function macro(string $name, ?callable $macro): void
     {
         FactoryImmutable::getDefaultInstance()->macro($name, $macro);
     }