Bump @deskpro/app-sdk from 5.1.1 to 6.0.4

Bumps @deskpro/app-sdk from 5.1.1 to 6.0.4.

---
updated-dependencies:
- dependency-name: "@deskpro/app-sdk"
  dependency-version: 6.0.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package.json

@@ -15,7 +15,7 @@
     "bumpManifestVer": "node ./bin/bumpManifestVer.js"
   },
   "dependencies": {
-    "@deskpro/app-sdk": "5.1.1",
+    "@deskpro/app-sdk": "6.0.4",
     "@deskpro/deskpro-ui": "^8.2.0",
     "@fortawesome/fontawesome-svg-core": "1.2.36",
     "@fortawesome/free-regular-svg-icons": "^6.7.2",