Update helm chart to use the latest slack configuration

[davidgolub]

The latest slack with app token that gets rid of the legacy bot does not work with a helm deployment, can we update the helm chart to reference the APP_TOKEN and BOT_TOKEN variables in the latest release? https://github.com/keel-hq/keel.sh/pull/53/files

[sbnarra]

Any update on this issue? My slack notifications have been failing since November with the below message.

time="2025-01-28T13:27:48Z" level=info msg="bot.slack.Configure(): SLACK_BOT_TOKEN must have the prefix \"xoxb-\", skip bot configuration."
time="2025-01-28T13:27:48Z" level=error msg="bot.Run(): can not get configuration for bot [slack]"

For now I've reverted to 0.19 with helm to keep notifications working.