Add core_version_requirement for Drupal 9 compatibility

Problem/Motivation

In order to use this module with Drupal 9, we need to include core_version_requirement in the module's info.yml file.

Steps to reproduce

- Create a new D9 site
- composer require drupal/honeycomb
- Error:
drupal/honeycomb 1.0.0-alpha1 requires drupal/core ~8.0 -> found drupal/core[8.0.0-beta6, ..., 8.9.x-dev] but the package is fixed to 9.1.8

Proposed resolution

Add the following to honeycomb.info.yml:

core: 8.x
core_version_requirement: ^8 || ^9

(The "core: 8.x" line is necessary to support Drupal 8.7.7 and earlier, which will not recognize core_version_requirement. Docs)

I ran the module through Drupal Check and did not see any other changes needed for D9 compatibility.