Install purge in CI, so the kernel tests can actually run.

Wiring the phpunit job was verified by running the unit tests inside the
CI image locally. That missed the kernel tests, which install quant_purger
and therefore need drupal/purge. CI only installed drupal/token, so all 14
purger kernel tests errored with "Unavailable module: 'purge'" on every
push since the job was added.

The suite passes locally because the harness has purge installed for the
end-to-end work. Verifying a CI change by running part of it locally was
not verifying it; the run on the pull request was.

Author: stooit

.github/workflows/ci.yml

@@ -35,8 +35,10 @@ jobs:
         run: drush si --db-url=mysql://root:drupal@mariadb:3306/drupal11 -y
         working-directory: /var/www/drupal
 
+      # token is required by quant_search. purge is required by quant_purger,
+      # whose kernel tests install it, so the suite cannot run without it.
       - name: Install module dependencies
-        run: composer --no-interaction --no-progress require drupal/token
+        run: composer --no-interaction --no-progress require drupal/token drupal/purge
         working-directory: /var/www/drupal
 
       # The image ships phpunit globally, but its bootstrap needs the test