message: fix: JOSS badge alt not inside img tag
diff: @@ -139,8 +139,9 @@ by Nextstrain team
  <a href="https://joss.theoj.org/papers/b0e8e7f231ddfc61616de6b56f32b79f">
  <img
  - src="https://joss.theoj.org/papers/b0e8e7f231ddfc61616de6b56f32b79f/status.svg">
  + src="https://joss.theoj.org/papers/b0e8e7f231ddfc61616de6b56f32b79f/status.svg"
  alt="JOSS submission status"
  + />
  </a>
  </p>
  