Drupal 11 compatibility fixes

Problem/Motivation

The add_to_head module is not currently compatible with Drupal 11. This lack of compatibility prevents users from upgrading their Drupal 10 sites to Drupal 11 if they rely on this module. Ensuring compatibility is essential to maintain the module's usability for sites upgrading to the latest version.

Steps to Reproduce

1. Install add_to_head on Drupal 11.
2. Observe errors or deprecated code notices.

Proposed Resolution

• Replace deprecated APIs with Drupal 11-compatible code.
• Test and validate functionality in Drupal 11.
• Update documentation as needed.

Remaining Tasks

• Identify and list all deprecated functions and methods used in the module.
• Update code to replace deprecated APIs with Drupal 11-compatible alternatives.
• Perform manual and automated testing in a Drupal 11 environment.
• Update module documentation to reflect any changes made for compatibility.
• Release a new version of the module tagged for Drupal 11 compatibility.

User Interface Changes

None.

API Changes

Minor updates to ensure compatibility with Drupal 11.

Data Model Changes

None.