fix: add Requires header fields and resolve implicit-nullable deprecations

Add "Requires at least" / "Requires PHP" to the plugin header to match
the versions already documented in README.md. Also explicitly mark
Term_Manager::__construct()'s $time and Term\UI::add_column_value()'s
$column_value / $custom_column parameters as nullable, since PHP 8.4+
deprecates relying on a "= null" default to imply a nullable type.

Author: torounit

includes/Term/UI.php

@@ -225,13 +225,13 @@ abstract protected function format_output( $value ): string;
 	/**
 	 * Output the value for the custom column
 	 *
-	 * @param string $column_value Custom column output. Default empty.
-	 * @param string $custom_column Name of the column.
-	 * @param int    $term_id Term ID.
+	 * @param string|null $column_value Custom column output. Default empty.
+	 * @param string|null $custom_column Name of the column.
+	 * @param int         $term_id Term ID.
 	 *
 	 * @return string|void
 	 */
-	public function add_column_value( string $column_value = null, string $custom_column = null, int $term_id = 0 ) {
+	public function add_column_value( ?string $column_value = null, ?string $custom_column = null, int $term_id = 0 ) {
 		if ( ! filter_input( INPUT_GET, 'taxonomy' ) && ! filter_input( INPUT_POST, 'taxonomy' ) ) {
 			return $column_value ?? '';
 		}

includes/Term_Manager.php

@@ -45,7 +45,7 @@ class Term_Manager {
 	 * @param string   $term_meta_key Term meta key.
 	 * @param int|null $time timestamp.
 	 */
-	public function __construct( string $post_meta_key, string $term_meta_key, int $time = null ) {
+	public function __construct( string $post_meta_key, string $term_meta_key, ?int $time = null ) {
 		$this->post_meta_key = $post_meta_key;
 		$this->term_meta_key = $term_meta_key;
 		$this->time          = $time ?? time();

schedule-terms.php

@@ -10,6 +10,8 @@
  * Text Domain:     schedule-terms
  * Domain Path:     /languages
  * Version: 1.3.2
+ * Requires at least: 6.7
+ * Requires PHP:      8.2
  *
  * @package Schedule_Terms
  */