Deploy app to cflinuxfs4 stack

.github/actions/deploy-proxy/action.yml

@@ -12,7 +12,7 @@ inputs:
     default: https://github.com/GSA-TTS/cg-egress-proxy.git
   proxy_version:
     description: git ref to be deployed
-    default: main
+    default: cflinuxfs4-deploy
 runs:
   using: composite
   steps:

manifest.yml

@@ -2,6 +2,7 @@
 applications:
   - name: notify-api-((env))
     buildpack: python_buildpack
+    stack: cflinuxfs4
     instances: 1
     disk_quota: 1G
     routes: