Composer install for build

Author: Maxime Rainville

.github/workflows/ci.yml

@@ -10,6 +10,7 @@ jobs:
     name: CI
     uses: silverstripe/gha-ci/.github/workflows/ci.yml@v1
     with:
+      composer_install: true
       # Use simple_matrix to limit the number of created jobs
       # phpunit.xml.dist has a large number of testsuites, all of which are tested with
       # multiple versions of php + databases in both the modules themselves and other recipes