deps: update web-modeler image to 8.8.0-alpha8 (#4114)

Author: bkenez

charts/camunda-platform-8.8/values.yaml

@@ -1413,7 +1413,7 @@ webModeler:
     registry: ""
     ## @param webModeler.image.tag can be used to set the Docker image tag for the WebModeler images (overwrites global.image.tag)
     # renovate: datasource=docker depName=camunda/web-modeler-restapi
-    tag: 8.8.0-alpha8-rc1
+    tag: 8.8.0-alpha8
     ## @param webModeler.image.pullSecrets can be used to configure image pull secrets, see https://kubernetes.io/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod
     pullSecrets: []