fix(deps): bump @octokit/app to fix web users (#2806)

The `verifyWithFallback()` function was missing from the web code in `@octokit/webhooks-methods`, and was only defined for Node, leaving users unable to use newer versions of `@octokit/webhooks` with this package

Author: wolfy1339

package-lock.json

@@ -21,7 +21,7 @@
     "test:typescript": "npx tsc --noEmit --declaration --noUnusedLocals --esModuleInterop --module node16 --strict --allowImportingTsExtensions --exactOptionalPropertyTypes test/typescript-validate.ts"
   },
   "dependencies": {
-    "@octokit/app": "^15.1.2",
+    "@octokit/app": "^15.1.3",
     "@octokit/core": "^6.1.3",
     "@octokit/oauth-app": "^7.1.4",
     "@octokit/plugin-paginate-graphql": "^5.2.4",