LearnDash LMS 4.13.0

* Feature - LearnDash Experiments.
* Feature - Virtual Instructor [Experiment].
* Tweak - Added filters: `learndash_experiments`, `learndash_model_virtual_instructor_applied_to_all_courses`, `learndash_model_virtual_instructor_applied_to_all_groups`, `learndash_model_virtual_instructor_avatar_url`, `learndash_model_virtual_instructor_banned_words`, `learndash_model_virtual_instructor_course_ids`, `learndash_model_virtual_instructor_custom_instruction`, `learndash_model_virtual_instructor_error_message`, `learndash_model_virtual_instructor_group_ids`, `learndash_model_virtual_instructor_message_contains_banned_words`, `learndash_model_virtual_instructor_name`, `learndash_module_ai_chatgpt_summarizer_command_generate_summary`, `learndash_module_ai_chatgpt_summarizer_last_preserved_messages_count`, `learndash_module_ai_chatgpt_summarizer_max_context_characters`, `learndash_module_ai_chatgpt_summarizer_messages_summary_content`, `learndash_module_ai_virtual_instructor_chat_session_initial_message`, `learndash_module_ai_virtual_instructor_chat_session_max_message_length`, `learndash_module_ai_virtual_instructor_chat_session_message_is_valid`, `learndash_module_ai_virtual_instructor_chat_session_message`, `learndash_module_ai_virtual_instructor_chat_session_storage_period`, `learndash_service_chatgpt_model_max_context_window_tokens`, `learndash_template_template_paths`.
* Tweak - Added actions: `learndash_experiments_experiment_init_after`, `learndash_experiments_experiment_init_before`, `learndash_experiments_init_after`, `learndash_experiments_init_before`, `learndash_post_setting_updated`.

* Fix - Resolved issue where the course progress could not be updated in some cases in a user profile.
* Fix - Resolved issue where Lifetime sales and Latest transactions widgets, present in the Course Dashboard, were causing fatal errors in some DB engines.
* Fix - Fixed compatibility issues with plugins using composer dependencies.
* Tweak - Updated functions: `learndash_process_mark_complete`, `learndash_process_user_course_progress_update`.

* Feature - Blended Learning.
* Fix - Stripe cancellation processing for finite subscriptions with no trial.
* Security - Tightened security around LearnDash Log.
* Security - Tightened security around quizzes.
* Performance - Course dashboard.
* Performance - Groups listing/editing page when there are many groups.
* Performance - Profile block when there are a lot of courses.
* Performance - Optimized functions: `learndash_get_certificate_count`, `learndash_get_groups_administrator_ids`, `learndash_get_groups_user_ids`, `learndash_get_user_stats`.
* Tweak - Fixed PHP 8.2 deprecation notices.
* Tweak - Improved the invoice PDF in the purchase email for subscriptions with no trial.
* Tweak - Make shared course steps option enabled by default.
* Tweak - Set minimum required PHP version to 7.4.
* Tweak - Updated constants: LEARNDASH_MIN_PHP_VERSION.
* Tweak - Updated the Stripe PHP library to version 13.
* Tweak - Added filters: `learndash_stripe_api_version`, `learndash_stripe_max_network_retries`.
* Tweak - Added functions: `learndash_course_steps_get_external_type`, `learndash_course_steps_is_external_attendance_required`, `learndash_course_steps_is_external`, `learndash_course_steps_map_external_type_to_label`, `learndash_process_password_reset_redirect`.
* Tweak - Updated functions: `learndash_course_get_step_completion_url`, `learndash_create_nonce`, `learndash_get_certificate_count`, `learndash_get_groups_administrator_ids`, `learndash_get_groups_user_ids`, `learndash_get_user_stats`, `learndash_mark_complete`, `learndash_process_mark_complete`, `learndash_reset_password_output`, `learndash_reset_password_set_user_new_password`, `learndash_stripe_api_version`, `learndash_stripe_max_network_retries`.
* Tweak - Updated templates: `ld30/templates/modules/course-steps.php`, `ld30/includes/helpers.php`, `ld30/templates/lesson/partials/row.php`, `themes/ld30/templates/topic/partials/row.php`, `ld30/templates/widgets/navigation/lesson-row.php`, `ld30/templates/widgets/navigation/topic-row.php`, `ld30/templates/quiz.php`.