dependabot should be configured to vendor on update for certain assets

[ctlong]

#539 (comment)

[ctlong]

Certain ruby apps which contained a vendor/cache were updated via dependabot PRs (#536, #537, #538, #539). However, dependabot is not configured to vendor dependencies when updating them.

We should manually fix the apps that were broken and update the dependabot.yml to vendor dependencies for them from now on.