Add core version requirement support for drupal 9

Confirmed that default_paragraphs have no errors and we need the above patch to make it compatible with D9. Marking RTBC'd.

This patch does not apply. I believe it needs a re-roll before it can successfully apply.

#2 applies to the project's repo, I tested using git apply. However, when I try to use this patch in composer I get a failure and the following .rej file:

***************
*** 3,7 ****
  description: Provides Paragraphs widget that allows us to select multiple paragraph types as defaults.
  package: Paragraphs
  core: 8.x
  dependencies:
    - paragraphs:paragraphs
--- 3,8 ----
  description: Provides Paragraphs widget that allows us to select multiple paragraph types as defaults.
  package: Paragraphs
  core: 8.x
+ core_version_requirement: ^8 || ^9
  dependencies:
    - paragraphs:paragraphs

My understanding it this is failing due to git only have two lines below the new line to anchor to. This is a new one for me but I was able to get a patch working with composer when I added the line either at the top of the file or between type and description. I've attached the latter patch.

As far as I can see #2 only does not apply because the additional lines that are added by Drupal.org packaging script. In the actual project repo those lines doesn't exist and the patch should apply.
To be sure I would still recommend using #8 because this one applies in all use cases I've tested.
Please go ahead with merging since without the patch the module cannot be installed on D9.
Thank you

I 100% agree with this to allow this module to work with D9.

Although it is super strange and feels out of place to have the ‘core_version_requirement’ line above the ‘description’ line in the info.yml file, this is the only way to make it apply cleanly via composer and compatible with D9.

In my work in upgrading to D9, I will be submitting similar patches to this to make those compatible as well.

None of above are working for Drupal 9.0.9.

1. I've added the patch into the composer.json file
2. composer require drupal/default_paragraphs

Impossible to install.
What am I doing wrong?

@WillemsB please post what patch you tried and the error message you got.

you can now pull these changes in via composer, composer require 'drupal/default_paragraphs:^2.0@RC'