Update devel version to work with Drupal 9

[geerlingguy]

The current Devel version only works with Drupal 8 and results in an error when building a new instance of Drupal VM using all the defaults. This happened after fixing #2062.

Issue Type

• Bug Report

Full console output

Your requirements could not be resolved to an installable set of packages.

Problem 1
- Conclusion: remove drupal/core-recommended 9.1.x-dev
- Conclusion: don't install drupal/core-recommended 9.1.x-dev
- Conclusion: don't install drupal/devel 1.2.0

Summary

See above.

[geerlingguy]

Testing a fix using:

drupal_composer_dependencies:
  - "drupal/devel:^4.0"