fix: add environment to discover job for secret access

The OIDC secrets are stored as environment secrets under
'region-discovery', so the job needs to reference that environment.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: simonjj

.github/workflows/region-discovery.yml

@@ -17,6 +17,7 @@ concurrency:
 jobs:
   discover:
     runs-on: ubuntu-latest
+    environment: region-discovery
     outputs:
       data_changed: ${{ steps.commit.outputs.data_changed }}
     steps:
@@ -101,4 +102,4 @@ jobs:
 
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v4