Remove deprecated rspec/integration

lib/telegram/bot/rspec/integration.rb

@@ -1,10 +0,0 @@
-require 'telegram/bot'
-Telegram::Bot.deprecation_0_15.warn(
-  "`require 'telegram/bot/rspec/integration'` is deprecated in favor of " \
-  "`require 'telegram/bot/rspec/integration/rails'`"
-)
-require 'telegram/bot/rspec/integration/rails'
-
-Telegram::Bot::RSpec.with_include_context do |config|
-  config.include_context 'telegram/bot/integration/rails', telegram_bot: true
-end