chore(github-growth): invite banner prompt (#53669)

src/sentry/utils/prompts.py

@@ -13,6 +13,7 @@ DEFAULT_PROMPTS = {
     "quick_trace_missing": {"required_fields": ["organization_id", "project_id"]},
     "code_owners": {"required_fields": ["organization_id", "project_id"]},
     "vitals_alert": {"required_fields": ["organization_id"]},
+    "github_missing_members": {"required_fields": ["organization_id"]},
 }