chore(deps): bump mjml from 4.15.3 to 4.18.0

Bumps [mjml](https://github.com/mjmlio/mjml/tree/HEAD/packages/mjml) from 4.15.3 to 4.18.0.
- [Release notes](https://github.com/mjmlio/mjml/releases)
- [Commits](https://github.com/mjmlio/mjml/commits/v4.18.0/packages/mjml)

---
updated-dependencies:
- dependency-name: mjml
  dependency-version: 4.18.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

packages/fxa-auth-server/package.json

@@ -100,7 +100,7 @@
     "keyv": "5.2.1",
     "lodash": "^4.17.23",
     "luxon": "^3.5.0",
-    "mjml": "^4.15.3",
+    "mjml": "^4.18.0",
     "moment-timezone": "^0.5.35",
     "mozlog": "^3.0.2",
     "mysql": "^2.18.1",