chore: various tweaks to support running tests in the CI

config/boot.rb

@@ -8,8 +8,8 @@ require 'bundler/setup' # Set up gems listed in the Gemfile.
 require_relative '../lib/postal/config'
 Postal.check_config!
 
-ENV['DATABASE_URL'] = Postal.database_url
 ENV['RAILS_ENV'] = Postal.config.rails&.environment || 'development'
+
 if ENV['PROC_NAME']
   $0="[postal] #{ENV['PROC_NAME']}"
 end