Add test values for environment vars, tell secret scanning to ignore them.

Author: alflanagan

.github/secret_scanning/allowlist.yaml

@@ -0,0 +1,4 @@
+---
+allowlist:
+  - 'DJANGO_SECRET_KEY: soveryverysecret'
+  - 'DJANGO_SUPERUSER_PASSWORD: lloyd'

docker-compose.yml

@@ -20,6 +20,10 @@ services:
     environment:
       DATABASE_URL: postgres://wagtail:development@postgres:5432/alloydflanagan
       DJANGO_SETTINGS_MODULE: alloydflanagan.settings.dev
+      DJANGO_SECRET_KEY: soveryverysecret
+      DJANGO_SUPERUSER_EMAIL: [email protected]
+      DJANGO_SUPERUSER_PASSWORD: lloyd
+      DJANGO_SUPERUSER_USERNAME: lloyd
     ports:
       - "8080:8080"