fix(ci): trigger PR gate on 0.83-merge base branches

The PR-gate workflow's `branches` filter only matched `main`, `*-stable`, and
`release/*`, so PRs targeting `0.83-merge` skipped every required check —
including the very Resolve-Hermes / Prebuild-macOS-Core jobs we want to
exercise on this branch.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Saadnajmi

.github/workflows/microsoft-pr.yml

@@ -3,7 +3,7 @@ name: PR
 on:
   pull_request:
     types: [opened, synchronize, edited]
-    branches: [ "main", "*-stable", "release/*" ]
+    branches: [ "main", "*-stable", "release/*", "0.83-merge" ]
 
 concurrency:
   # Ensure single build of a pull request. `main` should not be affected.