fix: Dotenv::Railtie is deprecated (#10515)

https://github.com/bkeepers/dotenv/pull/468

Renames Dotenv::Railtie => Dotenv::Rails

Co-authored-by: Sojan Jose <sojan@pepalo.com>

config/application.rb

@@ -11,7 +11,7 @@ Bundler.require(*Rails.groups)
 ## Load the specific APM agent
 # We rely on DOTENV to load the environment variables
 # We need these environment variables to load the specific APM agent
-Dotenv::Railtie.load
+Dotenv::Rails.load
 require 'ddtrace' if ENV.fetch('DD_TRACE_AGENT_URL', false).present?
 require 'elastic-apm' if ENV.fetch('ELASTIC_APM_SECRET_TOKEN', false).present?
 require 'scout_apm' if ENV.fetch('SCOUT_KEY', false).present?