Add strong typing for 3.0 version

src/Field/Traits/HtmlAttributes.php

@@ -45,13 +45,7 @@ trait HtmlAttributes {
 		return isset( $this->attributes[ $name ] );
 	}
 
-	/**
-	 * @param string  $name
-	 * @param ?string $default
-	 *
-	 * @return string
-	 */
-	public function get_attribute( string $name, $default = null ): string {
+	public function get_attribute( string $name, string $default = null ): string {
 		return $this->attributes[ $name ] ?? $default;
 	}
 }