[rails6][EvmDatabase] Fix .host

Rails 6 changed database configuration to support multi-db environments:

rails/rails#33637

So how one accesses the `@config` hash has changed.

The original error suggested the following:

    NotImplementedError: `ActiveRecord::Base.configurations` in Rails 6
    now returns an object instead of a hash. The `fetch_path` method is
    not supported. Please use `configs_for` or consult the documentation
    for supported methods.

However, there is no `[]` or `host` method, so it would require calling
`configs_for(env_name: ENV["RAILS_ENV"]).config['host']`.

This solution seemed like the more terse solution.

lib/evm_database.rb

@@ -133,7 +133,7 @@ def self.seed_classes(classes)
   private_class_method :seed_classes
 
   def self.host
-    ActiveRecord::Base.configurations.fetch_path(ENV['RAILS_ENV'], 'host')
+    (ActiveRecord::Base.configurations[ENV['RAILS_ENV']] || {})['host']
   end
 
   def self.local?