How to apply patch in Drupal 9?

@gilbert 

To apply a patch in Drupal 9, you will need to follow these steps:

1. Download the patch file.
2. Navigate to the root directory of your Drupal installation. This is the directory where the "core" and "vendor" directories are located.
3. Run the following command to apply the patch:patch -p1 < patch-file-name.patch Replace "patch-file-name.patch" with the name of the patch file you downloaded.
4. If the patch was applied successfully, you should see a message indicating that the patch was applied cleanly. If there are any conflicts, you will need to resolve them manually.
5. Clear the cache to make sure that the changes made by the patch are reflected on your site. You can do this by visiting the "Performance" page in the Drupal administrative interface, or by running the following command:drush cr

I hope this helps! Let me know if you have any questions.