Strip angle brackets

[dsubak]

What are the relevant tickets?

https://mit-office-of-digital-learning.sentry.io/issues/7656349183/events/394cbee32c4048f3a318b1b3c6cf8dd8/?environment=rc&project=5864687&query=is%3Aunresolved&referrer=previous-event

Description (What does it do?)

Just strips some formatting from the message ID given back by anymail. This means that it'll match what we get back from mailgun in the webhooks.

If you're using something like mailpit locally, this change has no effect.

How can this be tested?

Tests should pass - this is otherwise not feasible to test w/o a bunch of finagling and a mailgun account.

[github-actions]

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