Update maintenance branches in release scheduler

Signed-off-by: Rob Winch <362503+rwinch@users.noreply.github.com>

Author: rwinch

.github/workflows/release-scheduler.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         # List of active maintenance branches.
-        branch: [ main, 3.4.x, 3.5.x ]
+        branch: [ main, 4.0.x, 3.5.x ]
     runs-on: ubuntu-latest
     steps:
       - name: Checkout