Fresh install fails on Drupal 11.4: add symfony/runtime to config.allow-plugins

Problem/Motivation

On Varbase 9.2.x (Drupal ~11.4), a fresh build fails during composer install:

symfony/runtime contains a Composer plugin which is blocked by your allow-plugins config.

Drupal 11.4 pulls symfony/runtime, which ships a Composer plugin. It is not listed in config.allow-plugins in the vardot/varbase-project template's composer.json, so Composer's PluginManager blocks it and aborts the install.

Steps to reproduce

1. Create a project from the template: composer create-project vardot/varbase-project:9.2.x-dev (Drupal ~11.4).
2. Run composer install.
3. It fails with symfony/runtime contains a Composer plugin which is blocked by your allow-plugins config.

Proposed resolution

Add "symfony/runtime": true to config.allow-plugins in the template composer.json.

Remaining tasks

• ✅ File an issue about this project
• ❌ Addition/Change/Update/Fix to this project
• ❌ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ✅ Release varbase_project-9.2.0

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• fix: #3608495 Allow the symfony/runtime Composer plugin for Drupal 11.4