chore(deps): Bump wire-web-config-default-staging in /app-config (#15186

)

Bumps [wire-web-config-default-staging](https://github.com/wireapp/wire-web-config-default) from v0.31.14 to v0.31.15.
- [Commits](wireapp/wire-web-config-default@v0.31.14...31e6145)

---
updated-dependencies:
- dependency-name: wire-web-config-default-staging
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

app-config/package.json

@@ -1,6 +1,6 @@
 {
   "dependencies": {
     "wire-web-config-default-master": "https://github.com/wireapp/wire-web-config-wire#v0.31.16-0",
-    "wire-web-config-default-staging": "https://github.com/wireapp/wire-web-config-default#v0.31.14"
+    "wire-web-config-default-staging": "https://github.com/wireapp/wire-web-config-default#v0.31.15"
   }
 }