ci: throwaway check that only main enters the approver environment

Author: EtienneLescot

.github/workflows/approver-deny-check.yml

@@ -0,0 +1,12 @@
+name: approver deny check (throwaway)
+# Proves that a branch other than main cannot enter the approver environment.
+on:
+  push:
+    branches: [tmp/approver-deny-check]
+permissions: {}
+jobs:
+  probe:
+    runs-on: ubuntu-latest
+    environment: approver
+    steps:
+      - run: echo "entered the approver environment"