chore(deps): bump @iconify/svelte to 5 and postal-mime to 2 (#127)

- @iconify/svelte 4 -> 5: API for the default <Icon /> component is
  unchanged from a consumer perspective; build + svelte-check green.
- postal-mime 1 -> 2: still exports the default PostalMime class, so
  the existing `new PostalMime.default()` construction in
  src/lib/components/fallback/email.js continues to compile and bundle.
  v2 also introduces a static `PostalMime.parse(buf, options)` helper
  that is worth migrating to in a follow-up.

Verified: `npm run check` 0/0, `npm run build` green. Runtime test
of the email-fallback flow is recommended before flipping out of draft.

Refs encryption4all/dobby#25, #123

Co-authored-by: dobby-yivi-agent[bot] <275734547+dobby-yivi-agent[bot]@users.noreply.github.com>

Author: dobby-coder[bot]

package-lock.json

@@ -52,11 +52,11 @@
     "dependencies": {
         "@deltablot/dropzone": "^7.4.3",
         "@e4a/pg-js": "^0.10.0",
-        "@iconify/svelte": "^4.0.2",
+        "@iconify/svelte": "^5.2.1",
         "@privacybydesign/yivi-css": "^1.0.0-beta.4",
         "country-flag-icons": "^1.6.4",
         "libphonenumber-js": "^1.12.31",
-        "postal-mime": "^1.0.16",
+        "postal-mime": "^2.7.4",
         "web-streams-polyfill": "^4.2.0"
     }
 }