chore: point CHARTS_TREEISH back tro prerelease/lagoon_v218

Makefile

@@ -371,7 +371,7 @@ STERN_VERSION = v2.6.1
 CHART_TESTING_VERSION = v3.10.1
 K3D_IMAGE = docker.io/rancher/k3s:v1.28.6-k3s2
 TESTS = [nginx,api,features-kubernetes,bulk-deployment,features-kubernetes-2,features-variables,active-standby-kubernetes,tasks,drush,python,gitlab,github,bitbucket,services,workflows]
-CHARTS_TREEISH = keycloak-migrations
+CHARTS_TREEISH = prerelease/lagoon_v218
 TASK_IMAGES = task-activestandby
 
 # Symlink the installed kubectl client if the correct version is already