Enable 8.16 rest-api-spec updates, not 8.15

Author: pquentin

.github/workflows/update-rest-api-json.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        branch: ['main', '8.x', '8.15', '7.17']
+        branch: ['main', '8.x', '8.16', '7.17']
 
     steps:
       - uses: actions/checkout@v4