Update sentry config

[sislr]

breaking change from Sentry 6.0

recommended configuration taken from https://docs.sentry.io/platforms/ruby/guides/rails/data-management/sensitive-data/

[edmunteanu]

Looks good! Could be potentially made more compact like this:

      event.extra = filter.filter(event.extra) if event.extra
      event.user = filter.filter(event.user) if event.user
      event.contexts = filter.filter(event.contexts) if event.contexts

      event

[coorasse]

I like the compact version proposed by @edmunteanu