Fix missed_resource parameter

What does this MR do and why?

Addresses https://new-sentry.gitlab.net/organizations/gitlab/issues/691153/events/c6ebb3ba574f4129b6585cc4d47f8f28/?project=20

/builds/gitlab-org/quality/triage-ops/lib/missed_resource_helper.rb:9:in `missed_resource?': undefined method `due_date' for Fri, 15 Mar 2024:Date (NoMethodError)

Expected impact & dry-runs

These are strongly recommended to assist reviewers and reduce the time to merge your change.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-policies-with-a-dry-run on how to perform dry-runs for new policies.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/doc/reactive/best_practices.md#use-the-sandbox-to-test-new-processors on how to make sure a new processor can be tested.

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review